Assessment of Hydrology, Water Quality, and 

Trace Elements in Selected Placer-Mined Creeks in the 

Birch Creek Watershed near Central, Alaska, 2001–05

Prepared in cooperation with the Bureau of Land Management

Scientific Investigations Report 2007–5124

U.S. Department of the Interior

U.S. Geological Survey
Cover: Harrison Creek fall colors, August 31, 2005. View is looking north across 

Harrison Creek in foreground. (Photograph taken by Ben W. Kennedy, U.S. Geological 

Survey.)
Assessment of Hydrology, Water Quality, and 

Trace Elements in Selected Placer-Mined 

Creeks in the Birch Creek Watershed near 

Central, Alaska, 2001–05

By Ben W. Kennedy and Dustin E. Langley

Prepared in cooperation with the Bureau of Land Management

Scientific Investigations Report 2007-5124

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Kennedy, B.W., and Langley, D.E., 2007, Assessment of hydrology, water quality, and trace elements in selected 

placer-mined creeks in the Birch Creek watershed near Central, Alaska, 2001–05: U.S. Geological Survey Scientific 

Investigations Report 2007-5124, 50 p.
iii

Contents

Executive Summary ......................................................................................................................................1

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

Description of Study Area ...................................................................................................................2

Placer Mining ........................................................................................................................................4

Previous Studies ...................................................................................................................................4

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

Methods of Investigation .............................................................................................................................7

Field Methods........................................................................................................................................7

Data Analysis.........................................................................................................................................9

Data Summary Methods......................................................................................................................9

Results ...........................................................................................................................................................11

Overall Trends......................................................................................................................................11

Hydrology ....................................................................................................................................11

Birch Creek Daily Stream Gage......................................................................................11

Crest-Stage Gages ...........................................................................................................14

Stream Discharge Measurements.................................................................................15

Water Quality .............................................................................................................................15

Field Parameters ..............................................................................................................15

Major Ions..........................................................................................................................20

Nutrients.............................................................................................................................20

Mercury .............................................................................................................................21

Suspended Sediment .......................................................................................................22

Trace Elements in Streambed Sediment................................................................................25

Trace-Element Aquatic-Life Criteria..............................................................................25

Selected Trace Elements.................................................................................................25

Comparison of Paired-Site Results ..........................................................................................................29

Frying Pan Creek.................................................................................................................................29

Water Quality .............................................................................................................................30

Trace Elements in Streambed Sediment ...............................................................................32

Harrison Creek.....................................................................................................................................34

Water Quality .............................................................................................................................35

Trace Elements in Streambed Sediment ...............................................................................35

Summary and Conclusions.........................................................................................................................37

Acknowledgments.......................................................................................................................................38

References Cited..........................................................................................................................................38

Appendix A. Hydrology, Water-Quality, and Trace-Element Data .......................................................41
iv

Figures

Figure 1. Map showing location of stream-gage sites for the Birch Creek watershed

study near Central, Alaska.................................................................. 3

Figure 2. Map showing location of water-quality and streambed-sediment sample sites

in the upper Birch Creek watershed near Central, Alaska ........................... 6

Figure 3. Graph showing daily mean streamflow for Birch Creek stream-gage site

15392000 near Central, Alaska, water years 2001–05.................................... 12

Figure 4. Graph showing distribution of daily mean discharge by year for stream gage

(15392000) Birch Creek above Twelvemile Creek near Miller House, Alaska,

water years 2001–05 ........................................................................ 12

Figure 5. Graph showing distribution of daily mean discharge by month for stream

gage (15392000) Birch Creek above Twelvemile Creek near Miller House,

Alaska, water years 2001–05 ............................................................... 12

Figure 6. Graphs showing distribution of water-quality field parameters for selected

sites in the upper Birch Creek watershed near Central, Alaska, 2004 and 2005 ... 18

Figure 7. Piper diagram showing major-ion composition of samples at selected sites in

the upper Birch Creek watershed near Central, Alaska, 2004 and 2005 ............ 21

Figure 8. Piper diagram showing major-ion composition of samples at selected sites by

drainage basin in the upper Birch Creek watershed near Central, Alaska,

2004 and 2005................................................................................. 22

Figure 9. Graph showing distribution of daily suspended-sediment concentration data

from automated samplers for selected sites in Frying Pan Creek and Harrison

Creek near Central, Alaska, 2004 and 2005 ............................................. 25

Figure 10. Histogram plots for nine priority-pollutant trace elements in selected

streambed-sediment samples from the upper Birch Creek watershed near

Central, Alaska, 2005 ........................................................................ 26

Figure 11. Photograph showing reclaimed placer-mined area on Frying Pan Creek near

Central, Alaska, June 2004.................................................................. 29

Figure 12. Photograph of waste-rock piles and debris from historic placer mining on

Harrison Creek near Central Alaska, August 2005....................................... 34
Tables

Table 1. Description of stream-gage and water-quality sampling sites in the upper

Birch Creek watershed near Central, Alaska, 2001–05 ................................. 8

Table 2. Laboratory methods and minimum reporting levels for samples collected in

the upper Birch Creek watershed near Central, Alaska, 2003–05 ..................... 10

Table 3. Statistical summary of daily mean discharge by water year for stream gage

(15392000), Birch Creek above Twelvemile Creek near Miller House, Alaska,

2001–05 ....................................................................................... 13

Table 4. Statistical summary of daily mean discharge by month for stream gage

(15392000), Birch Creek above Twelvemile Creek near Miller House, Alaska,

water years 2001–05......................................................................... 13

Table 5. Water-year and period-of-record maximum discharge for Harrison Creek and

Frying Pan Creek crest-stage gages in the upper Birch Creek watershed near

Central, Alaska, 2002–05 .................................................................. 14

Table 6. Streamflow, water-quality field parameters, and suspended-sediment

concentrations at selected sites in the upper Birch Creek watershed near

Central, Alaska, 2003–05 .................................................................. 16

Table 7. Statistical summary of water-quality field parameters at selected sites in the

upper Birch Creek watershed near Central, Alaska, 2004 and 2005 .................. 19

Table 8. Summary of major-ion concentrations at selected sites in the upper Birch

Creek watershed near Central, Alaska, 2004 and 2005 ................................. 20

Table 9. Summary of nutrient concentrations at selected sites in the upper Birch Creek

watershed near Central, Alaska, 2004 and 2005 ....................................... 23

Table 10. Summary of mercury concentrations in water and streambed sediment at

selected sites in the upper Birch Creek watershed near Central, Alaska, 2005 ... 23

Table 11. Statistical summary of daily suspended-sediment concentrations at selected

sites in Frying Pan Creek and Harrison Creek near Central, Alaska, water

years 2004 and 2005 ........................................................................ 24

Table 12. Statistical summary of trace-element concentrations in streambed sediment at 

selected sites in the upper Birch Creek watershed near Central, Alaska, 2005 ... 27

Table 13. Summary of streambed-sediment-quality guidelines for nine priority-pollutant

trace elements in selected streambed-sediment samples from the upper

Birch Creek watershed near Central, Alaska, 2005 .................................... 28

Table 14. Statistical comparison of upstream and downstream water-quality field

parameters at selected sites in Frying Pan Creek and Harrison Creek near

Central Alaska, 2004 and 2005, by Wilcoxon rank-sum test ........................... 30

Table 15. Summary of upstream and downstream major-ion concentrations at selected

sites in Frying Pan Creek and Harrison Creek near Central, Alaska, 2004 and

2005 .......................................................................................... 31

Table 16. Summary of upstream and downstream nutrient concentrations at selected

sites in Frying Pan Creek and Harrison Creek near Central, Alaska, 2004 and

2005 .......................................................................................... 32

Table 17. Comparison of upstream and downstream trace-element concentrations in

streambed sediment for selected sites in Frying Pan Creek near Central,

Alaska, 2005 ................................................................................. 33

Table 18. Comparison of upstream and downstream trace-element concentrations in

streambed sediment for selected sites in Harrison Creek near Central,

Alaska, 2005 ................................................................................. 36
vi

Conversion Factors, Datums, and Abbreviations, Acronyms, 

and Definitions

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.00156 square mile (mi2

)

square mile (mi2

) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

gallon (gal) 0.003785 cubic meter (m3

) 

cubic foot (ft3

) 0.02832 cubic meter (m3) 

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

Pressure

atmosphere, standard (atm) 101.3 kilopascal (kPa)

bar 100 kilopascal (kPa) 

inch of mercury at 60oF (in. Hg) 3.377 kilopascal (kPa) 

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

 °C=(°F-32)/1.8.

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

 °F=(1.8×°C)+32.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25°C).

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

equivalent to parts per million (ppm), or micrograms per liter (μg/L), equivalent to parts per 

billion (ppb).

Datums

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29).

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

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

Abbreviations, Acronyms, and Definitions

AA atomic absorption 

ADEC Alaska Department of Environmental Conservation

ADNR Alaska Department of Natural Resources

ATSDR Agency for Toxic Substances and Disease Registry

ATV all-terrain vehicle

BLM Bureau of Land Management

CaCO3 calcium carbonate

CB-PEC consensus-based probable effect concentrations

CSG crest-stage gage

CVAF cold vapor atomic fluorescence

DGGS Alaska Division of Geological and Geophysical Surveys

EWI equal-width-increments

GFAA graphite furnace atomic absorption

IC ion chromatography

ICP inductively coupled plasma

ICPMS inductively coupled plasma mass spectrometry

LRL laboratory reporting level

MRL minimum reporting level

N nitrogen

NAWQA National Water-Quality Assessment

NWQL National Water Quality Laboratory

NWIS National Water Information System

P phosphorus

SQG sediment-quality guidelines

TMDL total maximum daily load

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

mg milligram

mm millimeter

μg/g microgram per gram

μm micrometer, micron

μS/cm microsiemens per centimeter at 25 degrees Celsius

p-value: A statistic term. A measure of probability that a difference between groups occurred 

by chance. For example, a p-value of .01 (p = .01) means there is a 1 in 100 chance the result 

occurred by chance. The smaller the p-value, the more likely it is that the difference between 

groups is caused by some other factor than random chance.

Water year: A continuous 12-month period selected to present hydrologic or meteorologic 

data including a complete annual hydrologic cycle. The water year used by the U.S. Geological 

Survey runs from October 1 through September 30 and is designated by the year it ends.
viii

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Assessment of Hydrology, Water Quality, and 

Trace Elements in Selected Placer-Mined Creeks in the 

Birch Creek Watershed near Central, Alaska, 2001–05

By Ben W. Kennedy and Dustin E. Langley

Executive Summary 

The U.S. Geological Survey, in cooperation with the 

Bureau of Land Management, completed an assessment of 

hydrology, water quality, and trace-element concentrations 

in streambed sediment of the upper Birch Creek watershed 

near Central, Alaska. The assessment covered one site on 

upper Birch Creek and paired sites, upstream and downstream 

from mined areas, on Frying Pan Creek and Harrison Creek. 

Stream-discharge and suspended-sediment concentration data 

collected at other selected mined and unmined sites helped 

characterize conditions in the upper Birch Creek watershed. 

The purpose of the project was to provide the Bureau of Land 

Management with baseline information to evaluate watershed 

water quality and plan reclamation efforts. Data collection 

began in September 2001 and ended in September 2005. 

There were substantial geomorphic disturbances in the 

stream channel and flood plain along several miles of Harrison 

Creek. Placer mining has physically altered the natural stream 

channel morphology and removed streamside vegetation. 

There has been little or no effort to re-contour waste rock 

piles. During high-flow events, the abandoned placer-mine 

areas on Harrison Creek will likely contribute large quantities 

of sediment downstream unless the mined areas are reclaimed. 

During 2004 and 2005, no substantial changes in nutrient 

or major-ion concentrations were detected in water samples 

collected upstream from mined areas compared with water 

samples collected downstream from mined areas on Frying 

Pan Creek and Harrison Creek that could not be attributed to 

natural variation. This also was true for dissolved oxygen, pH, 

and specific conductance—a measure of total dissolved solids. 

Sample sites downstream from mined areas on Harrison 

Creek and Frying Pan Creek had higher median suspendedsediment concentrations, by a few milligrams per liter, than 

respective upstream sites. However, it is difficult to attach 

much importance to the small downstream increase, less 

than 10 milligrams per liter, in median suspended-sediment 

concentration for either basin. During low-flow conditions 

in 2004 and 2005, previously mined areas investigated on 

Harrison Creek and on Frying Pan Creek did not contribute 

substantial suspended sediments to sample sites downstream 

from the mined areas. No substantial mining-related water- or 

sediment-quality problems were detected at any of the sites 

investigated in the upper Birch Creek watershed during lowflow conditions. 

Average annual streamflow and precipitation were near 

normal in 2002 and 2003. Drought conditions, extreme forest 

fire impact, and low annual streamflow set apart the 2004 

and 2005 summer seasons. Daily mean streamflow for upper 

Birch Creek varied throughout the period of record—from 

maximums of about 1,000 cubic feet per second to minimums 

of about 20 cubic feet per second. Streamflow increased and 

decreased rapidly in response to rainfall and rapid snowmelt 

events because the steep slopes, thin soil cover, and permafrost 

areas in the watershed have little capacity to retain runoff.

Median suspended-sediment concentrations for the 115 

paired samples from Frying Pan Creek and 101 paired samples 

from Harrison Creek were less than the 20 milligrams per 

liter total maximum daily load. The total maximum daily load 

was set by the U.S. Environmental Protection Agency for the 

upper Birch Creek basin in 1996. Suspended-sediment pairedsample data were collected using automated samplers in 2004 

and 2005, primarily during low-flow conditions. Suspendedsediment concentrations in grab samples from miscellaneous 

sites ranged from less than 1 milligram per liter during lowflow conditions to 1,386 milligrams per liter during a highflow event on upper Birch Creek.

Streambed-sediment samples were collected at six sites 

on Harrison Creek, two sites on Frying Pan Creek, and one 

site on upper Birch Creek. Trace-element concentrations 

of mercury, lead, and zinc in streambed sediment were less 

than the consensus-based probable-effect concentrations for 

aquatic life protection published in MacDonald and others 

(2000). Elevated arsenic, chromium, and nickel concentrations 

detected in several bed sediment samples indicate sediment 

input from mineralized local bedrock.

Water samples were collected for analysis of mercury 

concentration at ten sites during August and September 2005. 

Total-recoverable and total-dissolved-mercury concentrations 

for all samples were less than State and Federal drinking-water 

standards of 2.0 micrograms per liter.
Monitoring of suspended-sediment concentration, 

water quality, and trace elements in streambed sediment are 

recommended for Harrison Creek to document conditions 

during moderate to high flows and to monitor downstream 

impacts of reclamation work. Continued seasonal operation of 

the upper Birch Creek stream gage and crest-stage gages on 

Harrison Creek are recommended to document streamflow and 

to aid in ongoing flood-plain restoration and design work.

Introduction 

Historic placer-gold-mine operations have adversely 

affected water-quality and geomorphic conditions in the upper 

Birch Creek watershed near Central, Alaska. Birch Creek is 

a perennial clear-water stream that flows about 340 mi from 

its headwaters near Eagle Summit, through remote private, 

State, and Federal land in interior Alaska (fig. 1). In 1893, 

gold was discovered on Birch Creek in an area that later 

became famous as the Circle Mining District (Yeend and 

others, 1998). Placer-mine operations were active on the upper 

reaches of Birch Creek, and several of its tributaries in the 

Circle Mining District, from the 1890s until the beginning 

of World War II. Mining activity increased again in the 

mid-1970s with the rise in gold prices. The Alaska National 

Interest Land Conservation Act of 1980 designated a 126-mi 

section of Birch Creek as a component of National Wild 

and Scenic Rivers System. Through the same congressional 

action, large blocks of Federal land north and south of the 

wild-river corridor were converted to National Conservation 

Areas. The land and river corridor reclassifications limited 

mining operations in the Birch Creek watershed. The Bureau 

of Land Management (BLM) is tasked with assessment and 

reclamation of mined lands in the watershed with the goal of 

returning mined areas to a more scenic and natural state. 

The U.S. Geological Survey (USGS), in cooperation 

with the BLM, completed an assessment of hydrology, 

water quality, and trace-element concentrations in streambed 

sediment for portions of Birch Creek, Harrison Creek, and 

Frying Pan Creek. The assessment studied one stream-gage 

site on upper Birch Creek and paired crest-stage gage sites, 

upstream and downstream from mined areas, on Harrison 

Creek and Frying Pan Creek (fig. 1). The Birch Creek site was 

downstream from several historic placer-mine operations with 

varied reclamation. Harrison and Frying Pan Creek are placermined tributaries to Birch Creek. 

Description of Study Area

The upper Birch Creek study area encompasses an area of 

about 850 mi2 (fig. 1). Elevations range from about 900 ft near 

Central to peaks more than 4,000 ft near Eagle Summit and 

the headwaters of Birch Creek. Many of the hills and ridges 

are rounded and sparsely vegetated—tree line is approximately 

3,000 ft. Vegetation is primarily black and white spruce forest, 

with tundra at higher elevations. Willow and alder are common 

near streams. The highlands are underlain by Paleozoic schist 

and quartzite with Cretaceous and Tertiary granitic intrusions 

and minor mafic sills and dikes. The area has numerous highangle northeast trending faults. Bedrock is mineralized (Wiltse 

and others, 1995). Upper Birch Creek and Frying Pan Creek 

are underlain by quartzite and quartzitic schist. The South 

Fork of Harrison Creek and Harrison Creek flow eastward 

along a gradational geologic contact with mafic schist to the 

north and quartzite/quartzitic schist to the south (Yeend, 1991). 

The Circle Mining District is one of the richest placergold districts in Alaska, with an estimated total production 

of 1 million troy ounces since placer mining began in 

the late 1800s (Yeend, 1991). Widespread geochemical 

anomalies, and scattered mineral occurrences and prospects, 

indicate the region also may contain molybdenum porphyry, 

tungsten skarn, granite-related uranium deposits, lode tin 

deposits, platinum deposits of mafic igneous association, and 

sedimentary exhalative zinc-lead deposits (Foster and others, 

1994). Silt and stream gravels cover much of the lowland 

areas. Permafrost is discontinuous but prevalent, especially in 

steep valleys and north facing slopes (Davis, 2001). 

Annual precipitation in the area ranges from 10 to 

20 in/yr (Jones and Fahl, 1994) with upland areas receiving 

more precipitation than lower areas. The seasonal precipitation 

pattern is normally at a minimum in spring and at a maximum 

in late summer. Summer thunderstorms are common over the 

hills and upland areas. Summer maximum temperatures range 

from the upper 70s °F with extreme readings in the 90s; winter 

temperatures may be minus 50°F or lower for 2 or 3 weeks at 

a time (Western Regional Climate Center, 2006). Snow cover 

and freezing temperatures typically persist from October 

through April. Daylight hours range from a minimum of about 

4 hours in winter to more than 20 hours in summer. 

Local rivers normally begin freezing by the first week 

of October; melting of the river ice generally occurs in May. 

Streams typically have two or more peak discharge periods 

during open-water season. The first peaks are associated with 

snowmelt in May or June and subsequent peak discharges are 

associated with heavy precipitation events during summer or 

autumn. Flows increase and decrease rapidly in response to 

rainfall or rapid snowmelt events because the relatively steep 

slopes, thin soil cover, and permafrost in the watershed have a 

low capacity for retaining precipitation or meltwater. 

Naturally occurring events affecting water quality in the 

Birch Creek watershed include periodic heavy precipitation, 

forest fire activity, and landslides. During 2003, mid- and 

late-summer heavy precipitation resulted in extensive flooding 

in the Birch Creek watershed. The 2004 fire season was the 

worst on record in Alaska, approximately 6.5 million acres 

burned, with a majority of the large-fire activity occurring in 

central and eastern Alaska (National Climate Data Center, 

2004). Only minor portions of the study area burned in 2004. 

   Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
AK19-5003_fig01

UpperBirchCreekBasin

MedicineLake

Crooked

Creek

Porcupine

Creek

Birch

Creek

South Fork

Creek

Harrison

North Fork

Anvil Creek

Volcano Creek

Chums

Fork

Great Unknown Creek

Frying Pan

Creek

North Fork

Twelvemile 

 Creek

Ptarmigan

 Creek

South Fork

Twelvemile 

Creek 

Creek

Birch Porcupine Dome

Mastodon

Dome

PinnellMtn

Far

Mtn

Mt Ryan

Table

Mtn

Ketchem

Dome

Chena

Hot Springs

CircleHot Springs

Central

STEESE

HIGHWAY

Twelvemile

Summit

EagleSummit

Berry Camp

MillerHouse

See Figure 2 for details

Monument Creekweather station

15404800

15403000

15397700

15397500

15392000

15393900

15389980

15407200

15407500

15396100

15395900

15396000

0 10 MILES

0 10 KILOMETERS

144°20' 146°00’ 146°20’ 145°00’

65°35'

30'25'20'15'10'65°05'

20' 40' 40'

Base modified from U.S. Geological Survey digital line graphs andU.S. Geological Survey, Circle quadrangle, Alaska, 1:250,000, 1955Universe Transverse Mercator projection, zone 6

Precipitation recording siteUSGS stream-gaging station with number—With daily records

 Birch Creek above Twelvemile Creek near Miller House

USGS crest-stage gaging station with number 

15389980 Ptarmigan Creek near Mouth near Central 15393900 North Fork Twelvemile Creek near Miller House15395900 Upper Frying Pan Creek near Central15396000 Frying Pan Creek near Miller House15396100 Frying Pan Creek at Mouth near Central15397500 Great Unknown Creek near Central15397700 East Fork Great Unknown Creek near Central15403000 Volcano Creek near Central15404800 Anvil Creek near Central15407200 South Fork Harrison Creek near Central15407500 Harrison Creek above Bottom Dollar Creek near Central

1539200015393900

EXPLANATION

StudyArea

Figure 1. Location of stream-gage sites for the Birch Creek watershed study near Central, Alaska.

Introduction 
Widespread wildfire activity occurred in 2005 as well, more 

than 4.4 million acres burned across the State (National 

Climate Data Center, 2005). None of the study area burned 

during 2005. Smoke and particulate matter from the 2004 and 

2005 wildfires spread and persisted over the study area as well 

as large regions of Alaska and Canada.

Placer Mining

Prior to initiation of regulatory controls, placer-mine 

operations often created stream channel disturbances 

(Madison, 1981). Placer-mining operations were responsible 

for generating large quantities of sediment and increasing 

concentration of heavy metals—including arsenic, copper, 

lead, and mercury—downstream from mining activities (U.S. 

Environmental Protection Agency [USEPA], 1994). Placer 

mining typically involves rerouting streamflow into bypass 

channels and stripping vegetation and overburden to reach 

gold-bearing streambed and flood-plain gravels. As much 

as 90 percent of gold recovered from stream placers is in 

the lowermost 3 ft of gravel and in cracks and holes in the 

uppermost foot of bedrock (Yeend and others, 1998). Many 

abandoned placer mines left streams in bypass channels that 

are neither stable nor representative of the natural morphology 

of undisturbed reaches. Draglines, bulldozers, and excavators 

were used to move bed material to large trommel and wash 

plants that fed into a sluice with trough and riffle networks. 

Waste material was discharged to a series of tailing piles and 

settling ponds that were formed as mining progressed along 

the stream channel.

Fine-grained materials were washed downstream or 

buried in settling ponds. Vegetation does not readily grow 

on coarse tailings left at the land surface. Even if the site is 

re-contoured, the lack of soil or other fine-grained materials 

severely affects the stability of the restoration and lengthens 

the time required for natural re-vegetation. Without a binding 

mat of vegetation on the flood plain the unconsolidated 

tailings do not constrain the channel during floods. This 

can result in high sediment loads from mined areas during 

moderate to high flows. Excess sediment can irritate or clog 

the gills of invertebrates and fish and fills voids in gravel 

necessary for fish to spawn. Excess sediment also can blanket 

or erode algae, the base of the food chain for invertebrates and 

fish. 

In early placer-gold-mining operations, elemental 

mercury commonly was added to sluice-box troughs 

to increase recovery of fine-grained gold as placer ore 

was washed through ground sluices. Fine-grained gold 

amalgamates with mercury. Alpers and Hunerlach (2000) 

noted the estimated loss of mercury at historic placergold-mining operations in California was 10 to 30 percent 

per season, resulting in contaminated sediments at mine 

sites. Mercury was readily available to placer miners in 

Alaska. The Red Devil mine, near the town of Sleetmute 

on the Kuskokwim River, operated from 1933 until 1971 

and at one time was the largest mercury mine in the United 

States (Alaska Department of Environmental Conservation 

[ADEC], 1999). There are no known reports of elevated 

mercury concentrations in water, sediment, or fish tissue 

for the Birch Creek watershed. However, the National Park 

Service detected high levels of mercury and lead in sediment 

and elevated concentrations of zinc in water at a previously 

mined site on Coal Creek, about 44 mi southeast of Circle 

(Alaska Department of Environmental Conservation, 2005). 

Other mining districts in Alaska have documented mercury 

contamination associated with placer mining. The Agency for 

Toxic Substances and Disease Registry (ATSDR) completed 

a public health assessment of the City of Nome and Alaska 

Gold Company site and determined arsenic and mercury 

contamination were widespread throughout the Nome, Alaska, 

area (Agency for Toxic Substances and Disease Registry, 

1987). Preliminary sampling indicated arsenic and mercury 

contamination of water, sediment, and soil were attributable to 

gold extraction activities. On the other hand, there are areas in 

Alaska that have been mined extensively for placer gold, but 

do not have high mercury concentrations in water or sediment 

(MacFarlane, 2004). Nevertheless, based on the premise that 

procedures for early placer-mining operations in the upper 

Birch Creek watershed were similar to accepted practices of 

the time, and mercury was readily available in Alaska, some 

of the placer mines in the watershed probably used liquid 

mercury to increase recovery of fine-grained gold. 

Mercury contamination poses a risk to human health and 

the environment. Concentrations of mercury in filtered natural 

river water typically are very low, rarely exceeding tenths of 

1 microgram per liter (Hem, 1985). However, mercury may 

remain in soils and sediment for long periods, slowly releasing 

mercury compounds into the environment. Organic complexes 

such as methyl-mercury, CH3

Hg+, and other similar forms 

can be produced by methane-generating bacteria in contact 

with metallic mercury in lake or stream sediment (Wood and 

others, 1968). Methyl-mercury is the compound most readily 

incorporated into biological tissues and is a potent neurotoxin 

that impairs the nervous system (Alpers and Hunerlach, 2000). 

Mercury methylation is controlled by sulfate-reducing bacteria 

and other environmental factors including temperature, 

dissolved organic carbon, salinity, pH, and oxidation-reduction 

conditions. 

Previous Studies

Most previous studies of environmental effects associated 

with placer-mining activities in the Birch Creek watershed 

focused on surface-water-quality impacts that resulted from 

increased downstream sediment loads. Several studies of 

mined and unmined streams conducted in the Birch Creek 

 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
watershed have shown suspended-sediment concentrations 

were elevated in placer-mined streams (Weber, 1986; Mack 

and others, 1988; Ray, 1993; Packee, 1994; Vohden, 1999). 

Weber (1986) investigated the effects of placer-mining effluent 

on downstream water quality and aquatic macroinvertebrate 

populations in the east side of the Birch Creek watershed. The 

investigation concluded that the effects of increased siltation 

from placer-mining effluent are not restricted to the area 

immediately below active mining. Placer mining in the Birch 

Creek watershed resulted in profound changes in turbidity 

and invertebrate densities that persisted far downstream from 

mining input (Weber, 1986). Ray (1993) also investigated 

stream-sediment loads related to placer mining in the upper 

Birch Creek basin. Ray noted extensively disturbed creeks 

with no active mining contributed sediment for transport at 

a higher rate than unmined streams, but not as high a rate as 

actively mined streams. The investigation also noted a large 

percentage of the sediment is transported in short periods 

during high streamflows (storm events). At most sites, 

90 percent of the sediment was transported in 10 percent of the 

time. Additional hydrologic and water-quality investigations 

by Vohden (1999) also concluded that precipitation events 

played a major role in explaining elevated suspended-sediment 

concentrations at their sediment monitoring locations. In 1996, 

the USEPA issued a total maximum daily load (TMDL) for 

total suspended solids to meet water-quality standards for 

turbidity in Upper Birch Creek of 20 mg/L. Several tributaries 

in the Birch Creek drainage are listed in Section 303(d) 

as impaired waters because they exceeded water-quality 

criteria for turbidity (Alaska Department of Environmental 

Conservation, 2006). 

The Alaska Division of Geological and Geophysical 

Surveys (DGGS) monitored streamflow in Birch Creek above 

Twelvemile Creek from 1986 through 1994. Reported average 

flow for the period of record was 89 ft3/s (U.S. Environmental 

Protection Agency, 1996). The 2001 through 2005 USGS 

Birch Creek stream gage, site 15392000, was installed near the 

same location as the DGGS 1986 through 1994 Birch Creek 

stream gage. The DGGS reported a June 25, 1989, periodof-record peak flow of 1,940 ft3

/s for Birch Creek, with an 

estimated recurrence interval of 15 years (Ray, 1990). Peak 

flow was calculated using indirect methods.

Bjerklie and LaPerriere (1985) investigated surface and 

sub-surface waters in the Birch Creek basin in 1982. Their 

study reported mean levels of conductivity (113 μS/cm), 

alkalinity (51 mg/L), total hardness (72 mg/L), and pH (7.7) 

were not substantially different between Birch (mined) and 

Twelvemile (unmined) Creeks. However, concentrations of 

suspended solids, turbidity, and total iron were higher in Birch 

Creek than in Twelvemile Creek or Ptarmigan Creek before 

mining began. Mack and Moorman (1986) collected chemical 

and physical water-quality samples at 25 sites in the Birch 

Creek drainage. Analyses showed streams sampled above and 

below mining showed little, if any, lowering in pH, increase 

in sulfate concentration, or rise in specific conductivity 

below mined areas. Their findings indicated that the Alaska 

Department of Environmental Conservation (2003) maximum 

acceptable concentration of mercury for public drinking water 

(2 micrograms per liter [μg/L]) was exceeded slightly in both 

mined and unmined streams. Mack and Moorman (1986) 

suggested these findings might indicate slightly elevated 

levels of naturally occurring mercury in the area or laboratory 

analytical error. 

During the summer of 1984, mined and unmined stream 

sections in the Birch Creek watershed were inventoried to 

collect data on fish presence, habitat quality, and the densities 

and community structure of benthic invertebrates (Weber and 

Post, 1985). Weber and Post concluded that placer mining 

in the Birch Creek watershed resulted in elimination of the 

riparian vegetation and a higher proportion of silt and sand 

deposited on the stream bottom downstream from mined areas. 

They further concluded placer mining caused elimination of 

fish habitat, depressed aquatic invertebrate populations, and 

elimination of all fish from mined streams and from streams 

above active mining.

Townsend (1996) revisited mined and unmined streams 

in the Birch Creek drainage and reported the numbers of 

Arctic grayling and streams containing Arctic grayling 

increased from 1984 to 1990 and from 1990 to 1995. It was 

postulated that increased presence of Arctic grayling and 

other fish species in the upper Birch Creek drainage was the 

result of improved water quality, better mining practices and 

fewer mines, reclamation of stream and riparian habitats, and 

enhanced fish passage in active mining areas. Further studies 

by Townsend (2000) reported 19 juvenile chinook salmon 

were captured in Birch Creek and Harrison Creek. The study 

concluded that the presence of juvenile chinook salmon in 

three areas along 80 mi of Birch Creek indicates chinook 

salmon spawn somewhere between Crooked Creek and 

Twelvemile Creek.

Purpose and Scope

The purpose of this report is to summarize hydrology, 

water-quality, and streambed-sediment data collected at one 

site on upper Birch Creek and at paired sites, upstream and 

downstream from mined areas on Frying Pan Creek and 

Harrison Creek. The report also summarizes stream discharge, 

water-quality, and trace-element-concentration data collected 

at miscellaneous mined and unmined sites. The purpose of 

the study was to provide the BLM with baseline information 

necessary to evaluate water-quality issues and to plan and 

evaluate reclamation of mined lands in the Birch Creek 

watershed. Data collection began in September 2001 and 

ended in September 2005.

Introduction    
Sampling sites (figs. 1 and 2) were located upstream and 

downstream from previously mined reaches to characterize 

differences and similarities of natural channels and channels 

disturbed by placer mining in the watershed. The Harrison 

Creek watershed was affected by large-scale placer mining 

and was scheduled for selected flood-plain reclamation work 

in 2006. Several miles of the creek have been mined with little 

or no reclamation of waste-rock. A relatively small reach (less 

than 0.5 mi) was mined in the Frying Pan Creek watershed. 

Tailings were contoured to natural topography; however, little 

vegetation has been established over the disturbed area. A 

daily stream gage with satellite telemetry was installed at the 

Birch Creek above Twelvemile Creek site to provide real-time 

streamflow data. The Birch Creek stream-gage site also was 

used as a miscellaneous water-quality and streambed-sediment 

sample site. Several tributaries, upstream from the Birch Creek 

stream gage, were mined previously. Specific objectives of the 

study were:

Characterize and compare variations in water chemistry, 

including major-ion, nutrient, mercury, and suspendedsediment concentrations, as well as water-quality field 

parameters of pH, dissolved oxygen, water temperature, 

and specific conductivity for selected sites upstream and 

downstream from previously mined areas on Harrison 

Creek and Frying Pan Creek. 

Assess trace-element concentration levels in streambed 

sediments, particularly mercury because of its association 

with historic placer-gold-mine operations, and compare 

selected constituents to sediment-quality guidelines 

(SQG).

1.

2.

Upper

Birch

Creek

Basin

40' 20' 145°00’

65°15'

65°25'

20'

Creek

Birch

South Fork Creek

Harrison

North Fork

Chums

Fork

Creek

Unknown

Great

Frying Pan

North Fork

S FkTwelvemile

Creek

Bottom Dollar

Creek

Creek

Squaw

Gulch

Ptarmigan

Mastodon

Dome

Ketchem

Dome

STEESE

HIGHWAY

Berry Camp

0 10 MILES

0 10 KILOMETERS

Base modified from U.S. Geological Survey digital line graphs and

U.S. Geological Survey, Circle quadrangle, Alaska, 1:250,000, 1955

Universe Transverse Mercator projection, zone 6

EXPLANATION

Mercury sampling site with number

Stream gaging site

15392000 Birch Creek above Twelvemile Creek 

 near Miller House 

 15395900 Upper Frying Pan Creek near Central

 15396000 Frying Pan Creek near Miller House

15407200 South Fork Harrison Creek near Central

 15407500 Harrison Creek above Bottom Dollar

 Creek near Central

Miscellaneous sampling site

652149145074900 North Fork Harrison Creek 0.1 mile above mouth near Central

652129145001700 Harrison Creek 0.4 mile above Ptarmigan Creek near Central

652132144593900 Ptarmigan Gulch 0.2 mile above mouth near Central

652209144573700 Harrison Creek 1.3 miles below Ptarmigan Gulch near Central

652231144541200 Harrison Creek 0.2 mile above Squaw Creek near Central

15392000

652132144593900

652231144541200

652132144593900

652209144573700

652129145001700

652149145074900

15392000

15407200

15407500

15395900

15396000

Figure 2. Location of water-quality and streambed-sediment sample sites in the upper Birch Creek watershed near Central, 

Alaska.

 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Document study area streamflow characteristics by 

maintaining a stream gage near the headwaters of 

Birch Creek, maintaining crest-stage gages on selected 

tributaries, and measuring streamflow during field visits.

During 2001 through 2003, project tasks included 

maintaining a daily stream gage near the headwaters of Birch 

Creek and collecting streamflow and suspended-sediment 

samples at 10 crest-stage gages on 5 paired stream sites 

(fig. 1). Crest-stage gage sites on each creek were paired. The 

first gage was located upstream from previously mined areas 

and was paired with a second gage, downstream from mined 

areas. Access to 6 of the 10 gage sites was by helicopter. 

Because of recurring logistical difficulties associated with 

accessing remote sites by helicopter during inclement weather, 

as well as extended periods of forest-fire activity and smoke 

cover, the areal extent of the project was reduced for the 

2004 through 2005 field seasons. The daily stream gage with 

satellite telemetry was maintained near the headwaters of 

Birch Creek, site 15392000 (fig. 1). However, the number of 

crest-gage sites was reduced from 10 sites to 4: 2 paired sites 

on Harrison Creek and 2 paired sites on Frying Pan Creek 

(fig. 2) accessible by road or all-terrain vehicle (ATV).

Methods of Investigation 

Field methods and data analysis methods are presented 

in this section of the report. The section, “Field Methods” 

describes field procedures for measurement and collection 

of data for discharge, water-quality parameters, water 

chemistry, suspended sediment, and trace elements in 

streambed sediment. The section, “Data Analysis” describes 

laboratory methods and procedures, data-set compilation 

and data comparison methods, and statistical summaries 

of data. Statistical summaries presented in this report are 

intended to provide the reader with convenient summaries and 

comparisons of selected data. Primary data were compiled in 

the data section in appendix A to provide additional detail. 

Field Methods

Continuous-streamflow data were collected from 

September 2001 through September 2005 during openwater season, usually late May through September, at the 

Birch Creek stream gage above Twelvemile Creek, site 

15392000 (table 1). The stream gage was equipped with 

satellite telemetry and recorded stage, precipitation, and 

air temperature. During site visits, field measurements of 

streamflow were made using a Price type AA or pygmy 

current meter and established procedures described in Rantz 

and others (1982). Streamflow data from field visits were 

used to develop a rating curve to compute streamflows from 

continuous-stage data recorded at the gage station following 

standard USGS procedures in Rantz and others (1982). 

3. Crest-stage gage streamflow was monitored intermittently 

during open-water season at 10 crest-stage gage sites during 

2001 through 2003, and regularly at 4 sites from 2004 through 

2005 (table 1). Crest-stage gage records for selected sites were 

computed using standard USGS procedures (Rantz and others, 

1982). Restricted access to remote sites prevented sufficient 

data records for calculation of peak streamflow for locations 

on Ptarmigan Creek site 15389980, North Fork of Twelvemile 

Creek site 15393900, Great Unknown Creek site 15397500, 

East Fork Great Unknown Creek site 15397700,Volcano Creek 

site 15403000, and Anvil Creek site 15404800 (table 1).

Channel cross-section geometry and water-surface 

profiles were determined by optical surveys for calculation of 

indirect discharge. Channel cross-section plots for South Fork 

of Harrison Creek (fig. A1) and Harrison Creek (fig. A2) creststage gage sites were included in appendix A for reference 

because flood-plain reclamation work was scheduled to begin 

in 2006 on Harrison Creek, below the confluence of the North 

Fork and South Fork of Harrison Creek (fig. 2).

Water-quality field parameters of water temperature, 

specific conductance, dissolved-oxygen concentration, and pH 

were measured using a multi-probe sonde during site visits 

at the Birch Creek stream gage site 15392000, at Frying Pan 

Creek sites 15395900 and 15396000, and at Harrison Creek 

crest-stage gage sites 15407200 and 15407500 (table 1). The 

multi-probe sonde was calibrated streamside during each 

field visit using standard solutions and adjusted according to 

procedures in Wagner and others (2000) as well as periodically 

checked in the lab with calibrated meters. Direct measurement 

of water-quality parameters were made following standard 

stabilization criteria (U.S. Geological Survey, 1998). 

Nutrient, alkalinity, and major-ion water samples were 

collected during late summer 2004 at the Frying Pan and 

Harrison Creek crest-stage gage sites noted previously. 

Samples for nutrients, alkalinity, major ions, mercury in 

water, and selected trace elements in streambed sediment 

were collected at the same sites, as well as at the Birch Creek 

gage site, 15392000, during August and September 2005. 

Equipment blanks were sent to the National Water-Quality 

Laboratory (NWQL) for analysis at the beginning of the 

2004 and 2005 field seasons. Four miscellaneous sites on 

Harrison Creek, 652149145074900, 652129145001700, 

652132144593900, and 652209144573700, were sampled 

for mercury concentration in water and trace elements 

in streambed sediment (fig. 2) because these areas were 

scheduled for flood-plain reclamation work in 2006. Water 

samples for nutrients, alkalinity, major ions, and mercury were 

collected by equal-width-increment (EWI) methods using 

a handheld DH-81 sampler, with 1-liter (L) polyethylene 

sampler bottles, and a D-77 nozzle attachment. Samples were 

composited in a churn splitter made from inert material for 

dispensing sample aliquots to each analytical bottle (U.S. 

Geological Survey, 1998).

An automated water sampler was deployed to collect 

suspended-sediment samples at the Birch Creek gage site 

15392000 in July 2003, but was lost during a late July high 

Methods of Investigation 
Table 1. Description of stream-gage and water-quality sampling sites in the upper Birch Creek watershed near Central, Alaska, 

2001–05.

[Latitude and longitude coordinates in North American Datum 1927 Alaska (NAD27AK) in degrees, minutes, and seconds. Abbreviations: USGS, U.S. 

Geological Survey; mi2, square mile]

USGS site 

identification 

No.

Site name Latitude Longitude

Contributing 

drainage area 

(mi2

)

Remarks

15389980 Ptarmigan Creek near mouth, 

near Central, Alaska

65°26 ́24 ̋ 145°31 ́34 ̋ 19.2 Crest-stage gage—site not monitored in 

2004–05

15392000 Birch Creek above Twelvemile 

Creek, near Miller House, 

Alaska

65°23 ́33 ̋ 145°42 ́45 ̋ 89.2 Stream gage with satellite telemetry, near 

Steese Hwy. mile 93. Mercury sample 

site—water and streambed sediment 

15393900 North Fork Twelvemile Creek 

near Miller House, Alaska

65°24 ́03 ̋ 145°44 ́18 ̋ 23.2 Crest-stage gage—site not monitored in 

2004–06

15395900 Upper Frying Pan Creek near 

Central, Alaska

65°19 ́37 ̋ 145°33 ́01 ̋ 8.1 Crest-stage gage above mined area. Mercury 

sample site—water and streambed sediment 

15396000 Frying Pan Creek near Miller 

House, Alaska

65°19 ́18 ̋ 145°33 ́02 ̋ 14.7 Crest-stage gage below mined area, installed 

summer 2004. Mercury sample site—water 

and streambed sediment 

15396100 Frying Pan Creek at mouth, 

near Central, Alaska

65°16 ́58 ̋ 145°33 ́33 ̋ 20.6 Crest-stage gage—remote site not accessed in 

2004–05

15397500 Great Unknown Creek near 

Central, Alaska

65°17 ́38 ̋ 145°24 ́00 ̋ 18.6 Crest-stage gage—remote site not accessed in 

2004–05

15397700 East Fork Great Unknown 

Creek near Central, Alaska

65°17 ́36 ̋ 145°23 ́20 ̋ 20.4 Crest-stage gage—remote site not accessed in 

2004–05

15403000 Volcano Creek near Central, 

Alaska

65°08 ́09 ̋ 145°28 ́39 ̋ 5.6 Crest-stage gage—remote site not accessed in 

2004–05

15404800 Anvil Creek near Central, 

Alaska

65°12 ́42 ̋ 145°14 ́25 ̋ 20.4 Crest-stage gage—remote site not accessed in 

2004–05

15407200 South Fork Harrison Creek 

near Central, Alaska

65°21 ́52 ̋ 145°15 ́25 ̋ 9.1 Crest-stage gage site above mined area. 

Mercury sample site, water and streambed 

sediment 

652149145074900 North Fork Harrison Creek 0.1 

mile above mouth, near 

Central, Alaska

65°21 ́49 ̋ 145°07 ́49 ̋ 25.3 Placer mined tributary to Harrison Creek. 

Mercury sample site—water and streambed 

sediment 

652129145001700 Harrison Creek 0.4 mile above 

Ptarmigan Gulch, near Central, 

Alaska

65°21 ́29 ̋ 145°00 ́17 ̋ 56.4 Mercury sample site—water and streambed 

sediment 

652132144593900 Ptarmigan Gulch 0.2 mile above 

mouth, near Central, Alaska

65°21 ́32 ̋ 144°59 ́39 ̋ 3.9 Mercury sample site—water sample only

652209144573700 Harrison Creek 1.3 miles below 

Ptarmigan Gulch, near Central, 

Alaska

65°22 ́09 ̋ 144°57 ́37 ̋ 62.7 Mercury sample site—water and streambed 

sediment 

652231144541200 Harrison Creek 0.2 mile above 

Squaw Creek, near Central, 

Alaska

65°22 ́31 ̋ 144°54 ́12 ̋ 67.5 Mercury sample site—water and streambed 

sediment 

15407500 Harrison Creek above Bottom 

Dollar Creek, near Central, 

Alaska

65°22 ́45 ̋ 144°49 ́58 ̋ 71.6 Crest-stage gage site below mined area. 

Mercury sample site—water and streambed 

sediment 

 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
flow that undercut the stream bank where the sampler was 

deployed. During 2004 and 2005, automated samplers were 

deployed after spring snowmelt to collect daily suspendedsediment samples at two crest-stage gage sites on Frying Pan 

Creek (15395900 and 15396000) and two crest-stage gage 

sites on Harrison Creek (15407200 and 15407500) (fig. 2). 

Daily 1-L samples were collected at 10:00 p.m. The paired 

crest-stage gage sites were located upstream and downstream 

from placer-mined areas. Suspended-sediment EWI samples 

were collected during field visits to verify sample accuracy 

of the automated sampler. EWI sample concentrations were 

typically within ± 2 mg/L of automated sampler suspendedsediment concentration samples. Miscellaneous suspendedsediment grab (point) samples were collected from stream 

banks during high flows.

Streambed sediment samples for selected trace elements 

were collected to address concerns that substantial amounts 

of mercury in sediments may be disturbed during stream 

channel and flood plain reclamation work. Collection and 

field processing of streambed-sediment samples followed 

established USGS National Water-Quality Assessment 

(NAWQA) Program protocols (Shelton and Capel, 1994). 

Streambed sediments were collected from depositional zones 

selected to represent various streamflow regimes. Sampling 

was confined to the upper 1–4 in. of streambed sediment. At 

each sampling site, five to eight subsamples were collected, 

composited in a glass bowl, and passed through a 63-micron 

wet sieve. Eight replicate samples for total mercury were 

split and processed from the composite samples to evaluate 

sample mercury concentration variance. Samples were shipped 

overnight to the USGS NWQL in Arvada, Colorado, for 

analyses. Links to NWQL quality-assurance and analytical 

procedures are available at the NWQL Web page (http://

wwwnwql.cr.usgs.gov/USGS/USGS_srv.html).

Data Analysis

Water samples collected for major-ion and nutrient 

analysis were analyzed at the USGS NWQL in Lakewood, 

Colorado, using standard analytical techniques described in 

Fishman (1993), Fishman and Friedman (1989), and Patton 

and Truitt (2000). Laboratory analysis of water samples 

collected for analysis of total mercury in filtered (0.45 μm) 

and unfiltered samples were analyzed at the USGS NWQL 

in Lakewood, Colorado, using standard analytical techniques 

described in Garbarino and Damrau (2001). Filtered (0.63 μm) 

streambed-sediment samples were collected and analyzed 

for selected trace elements at the USGS Central Mineral 

Resources Team-Analytical Chemistry, Denver, Colorado, 

using standard techniques described in Arbogast (1996), 

Taggart (2002), and Briggs and Meier (1999). Suspendedsediment concentration samples were analyzed at the USGS 

Cascades Volcano Observatory Sediment Laboratory in 

Vancouver, Washington, and analyzed according to methods 

described by Guy (1977).

Laboratory methods and minimum reporting limits for 

water and sediment samples collected during the study are 

listed in table 2. All stream discharge, water-quality, and 

streambed-sediment data are available to the public at the 

USGS National Water Information System (NWIS) at http://

waterdata.usgs.gov/nwis.

Data Summary Methods

Hydrologic data were summarized using time-series plots 

of daily mean flow and box plots to characterized period-ofrecord, annual, and monthly flow statistics. 

Water-quality data for field parameters, major ions, 

nutrients, suspended sediment, and mercury in water were 

summarized using descriptive statistics, piper plots, and 

box plots. Spatial differences for field parameters were 

summarized using a Wilcoxon rank-sum test. The Wilcoxon 

rank-sum test is a nonparametric test equivalent to the MannWhitney U test. It does not require a normal distribution to 

detect differences between two populations based on random 

samples from those populations (Helsel and Hirsch, 1992). 

Statistical comparisons were reported as significant for tests 

with calculated p-values less than or equal to 0.01. The p-value 

is a measure of probability that a difference between groups 

occurred by chance. For example, a p-value of 0.01 (p = 0.01) 

means there is a 1 in 100 chance the result occurred by 

chance. The smaller the p-value, the more likely the difference 

between groups was caused by some other factor than random 

chance.

 Trace-element data were compiled using descriptive 

statistics and comparative tables. Histograms were used to 

illustrate variations in selected trace-element concentrations. 

National median trace-element concentrations for nine U.S. 

Environmental Protection Agency (1994) priority pollutants—

arsenic, cadmium, chromium, copper, lead, mercury, nickel, 

selenium, and zinc—were compared to study area sample 

results in a summary table. 

Methods of Investigation 
Table 2. Laboratory methods and minimum reporting levels for samples collected in the upper Birch Creek watershed near Central, 

Alaska, 2003–05.

[MRL is defined by the NWQL as the smallest measured concentration of a substance that can be reliably measured by using a given analytical method. It is the 

“less-than” value reported when an analyte either is not detected or is detected at a concentration less than the MRL. Minimum reporting levels and reporting 

units given for NWQL Schedule constituents may vary from actual analytical results reported by NWQL for a particular sample as LRL because of instrument 

calibration, sample matrix interference, or other factors. Method: AA, atomic absorption; CVAF, cold vapor atomic fluorescence; EWI, equal-width-increment; 

GFAA, graphite furnace atomic absorption; IC, ion chromatography; ICP, inductively coupled plasma; ICPMS, inductively coupled plasma mass spectrometry. 

Abbreviations: LRL, laboratory reporting level; MRL; minimum reporting level; NWQL, National Water Quality Laboratory; ft3/s, cubic foot per second; mg/L, 

milligram per liter; N, nitrogen: P, phosphorus; μg/L, microgram per liter; μg/g, microgram per gram; °C, degrees Celsius; μS/cm, microsiemens per centimeter 

at 25°C; CaCO3, calcium carbonate; pct, percent]

Property or constituent

NWQL 

catalog

units

Method

MRL/LRL

Field Analytical

Field properties

Discharge ft3/s Current meter Mid-interval Variable 

Specific conductance μS/cm Point/EWI Electrode 1

pH units Point/EWI Electrode .1

Water temperature mg/L Point/EWI Electrode .1

Dissolved oxygen mg/L Point/EWI Electrode .1

Major ions: Schedule 2701 NWQL

Calcium, dissolved mg/L EWI ICP 0.02

Chloride, dissolved mg/L EWI IC .20

Fluoride, dissolved mg/L EWI Ion selective electrode .10

Iron, dissolved μg/L EWI ICP 6

Magnesium, dissolved mg/L EWI ICP .008

Manganese, dissolved μg/L EWI ICP .6

Potassium, dissolved mg/L EWI ICP .16

Silica, dissolved mg/L EWI ICP .04

Sodium, dissolved mg/L EWI ICP .20

Sulfate, dissolved mg/L EWI IC .18

Acid-neutralizing capacity, lab as CaCO3 mg/L EWI Titration 5

Nutrients: Schedule 1119 NWQL

Nitrite, dissolved as N mg/L EWI Colorimetry 0.002

Nitrite plus nitrate, dissolved as N mg/L EWI Colorimetry .016

Nitrogen, ammonia, dissolved as N mg/L EWI Colorimetry .010

Nitrogen, ammonia plus organic, dissolved as N mg/L EWI Colorimetry .10

Nitrogen, ammonia plus organic, total as N mg/L EWI Colorimetry .10

Phosphorus, total as P mg/L EWI Colorimetry .004

Phosphorus, dissolved as P mg/L EWI Colorimetry .004

Phosphorus, dissolved orthophosphate as P mg/L EWI Colorimetry .006

Mercury: Lab codes 2707, 2708 NWQL

Mercury, dissolved μg/L EWI CVAF 0.010

Mercury, total μg/L EWI CVAF .010

Streambed sediment trace elements: Schedule 2420 NWQL

Aluminum (Al) μg/g Composite ICPMS 50

Antimony (Sb) μg/g Composite ICPMS .04

Arsenic (As) μg/g Composite ICPMS, GFAA 1 

Barium (Ba) μg/g Composite ICPMS .2

Beryllium (Be) μg/g Composite ICPMS .03

Bismuth (Bi) μg/g Composite ICPMS .06

Cadmium (Cd) μg/g Composite GFAA .007

Calcium (Ca) μg/g Composite ICPMS 100

Cerium (Ce) μg/g Composite ICPMS .1

Chromium (Cr) μg/g Composite ICPMS .5

Cobalt (Co) μg/g Composite ICPMS 0.03

10 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Property or constituent

NWQL 

catalog

units

Method

MRL/LRL

Field Analytical

Streambed sediment trace elements: Schedule 2420 NWQL—Continued

Copper (Cu) μg/g Composite ICP, GFAA 2 

Gallium (Ga) μg/g Composite ICP, GFAA .02

Iron (Fe) μg/g Composite AA, ICP 50

Lanthanum (La) μg/g Composite GFAA .05

Lead (Pb) μg/g Composite GFAA .4

Lithium (Li) μg/g Composite AA, ICP .3

Magnesium (Mg) μg/g Composite AA, ICP 6

Manganese (Mn) μg/g Composite AA, ICP .7

Mercury (Hg) μg/g Composite CVAF .020

Molybdenum (Mo) μg/g Composite ICPMS .50

Nickel (Ni) μg/g Composite ICPMS .3

Niobium (Nb) μg/g Composite ICPMS .1

Phosphorus (P) μg/g Composite ICPMS 5

Potassium (K) μg/g Composite ICPMS 20

Scandium (Sc) μg/g Composite ICPMS .04

Selenium (Se) μg/g Composite ICPMS .1

Silver (Ag) μg/g Composite ICPMS 2

Sodium (Na) μg/g Composite ICPMS 20

Strontium (Sr) μg/g Composite ICPMS .8

Sulfur (S) pct Composite ICPMS .05

Thallium (Tl) μg/g Composite ICPMS .08

Thorium (Th) μg/g Composite ICPMS 1.0

Titanium (Ti) μg/g Composite ICPMS .005

Uranium (U) μg/g Composite ICPMS .1

Vanadium (V) μg/g Composite ICPMS 2

Yttrium (Y) μg/g Composite ICPMS 1

Zinc (Zn) μg/g Composite ICP, AA 2

Organic carbon pct Composite ICPMS .01

Inorganic carbon pct Composite ICPMS .01

Organic plus inorganic carbon, total pct Composite ICPMS .01

Sediment

Sediment, suspended, concentration mg/L Point/grab/EWI Gravimetric 1

Results 11

Table 2. Laboratory methods and minimum reporting levels for samples collected in the upper Birch Creek watershed near Central, 

Alaska, 2003-05.—Continued

deep reaches and gradients of about 2 percent or less. Bed 

material typically was coarse: pebble, cobble, and boulder, 

with only minor in-stream fine-grained sediments. Runoff 

intensity was high. Flows increased and decreased rapidly in 

response to major rainfall and snowmelt events because the 

relatively steep slopes, thin soil cover, and permafrost areas in 

the watershed had a low capacity for retaining precipitation or 

meltwater. Many of the drainages were split or single channels 

with relatively wide flood plains or incised channels with no 

flood plain (fig. A3).

Birch Creek Daily Stream Gage

Hydrologic data from the Birch Creek stream gage (site 

15392000) were summarized using a time-series plot of daily 

mean streamflow (fig. 3) to characterize seasonal and longterm flow patterns. Seasonal discharges were highly variable. 

Results

Study results are divided into two sections. The first 

section describes overall trends in the data set. The second 

section compares samples from paired sites, upstream and 

downstream from mined areas on Frying Pan Creek and 

Harrison Creek.

Overall Trends

Hydrology

Hydrologic characteristics of the Birch Creek watershed 

were compiled from stream-gage records, crest-stage gage 

records, discharge measurements, field-site inspections, and 

surveys of stream-channel cross sections. Generally, channels 

were alternating pool and riffle sequences with occasional 
Figure 3. Daily mean streamflow for Birch Creek stream-gage site 15392000 near Central, Alaska, water years 2001–05.

Figure 4. Distribution of daily mean discharge by year 

for stream gage (15392000) Birch Creek above Twelvemile 

Creek near Miller House, Alaska, water years 2001–05.

Figure 5. Distribution of daily mean discharge by month 

for stream gage (15392000) Birch Creek above Twelvemile 

Creek near Miller House, Alaska, water years 2001–05.

0

A S O N D J F M A M JJ A S O N D J F M A M JJ A S O N D J F M A M JJ A S O N D J F M A M JJ A S O N

200

400

600

800

1000

1200

2001 2002 2003 2004 2005

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

No data No data No data No data

2001 2002 2003 2004 2005

34 140 170 151 153

DAILY MEAN DISCHARGE, IN CUBIC FEET PER YEAR

101

102

103

170 Number of observations

100th percentile

75th percentile

Median

25th percentile

0 percentile

EXPLANATION

MAY JUNE JULY AUG SEPT OCT

97 120 124 128 150 29

DAILY MEAN DISCHARGE, IN CUBIC FEET PER MONTH 

101

102

103

124 Number of observations

100th percentile

75th percentile

Median

25th percentile

0 percentile

EXPLANATION

12 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05

Typically, there were two or more periods of sharp discharge 

peaks. The first peak flows were associated with snowmelt 

runoff. Magnitude of the snowmelt runoff peaks depended 

on the volume of accumulated winter snowpack, timing 

of snowpack melting, and precipitation events. Additional 

discharge peaks, of similar or greater magnitude, occurred after 

spring snowmelt and were related to the location, duration, and 

intensity of precipitation events. 

Statistical summaries of the Birch Creek daily mean 

discharge data were compiled by year in table 3 and by month 

in table 4. Summary statistics and daily mean discharge 

values are also available online at the NWIS web site (http://

waterdata.usgs.gov/nwis). 

Daily mean peak discharges associated with snowmelt 

in late May and early June ranged from a minimum of about 

400 ft3/s in 2003 to maximums of about 1,000 ft3/s in 2002 

and 2005. Daily mean peak discharges associated with rainfall 

events were about 1,000 ft3/s and occurred in June 2002, July 

and September 2003, and June 2005 (figs. 4 and 5). Spring 

discharges associated with snowmelt were low in 2003 

because interior Alaska snowpack was less than 50 percent 

of average (Rozell, 2003). For 2004 and 2005 summer 

precipitation was less than normal (National Climate Data 

Center, 2005) and associated mid to late-summer discharge 

peaks were less than 600 ft3/s. Maximum daily mean peak 
Table 3. Statistical summary of daily mean discharge by water year for stream gage (15392000), Birch Creek above Twelvemile 

Creek near Miller House, Alaska, 2001–05.

[Yearly streamflow recorded during open water season, May–October, does not include winter streamflow under ice cover. Abbreviations: ft3/s, cubic 

foot per second]

Water year

Discharge (ft3

/s)

 Number

of days Dates discharge recorded

Minimum 25th 

Percentile Median 75th 

Percentile Maximum

2001 32 48 68 87 115 34 Partial year: 34 days, 08-28 to 09-30

2002 27 79 108 194 1,130 140 Dates: 10-01 to 10-02; 05-16 to 09-30

2003 13 44 85 200 1,050 170 Dates: 10-01 to 10-17; 05-01 to 09-30

2004 13 18 28 76 641 151 Dates: 10-01 to 10-10; 05-13 to 09-30

2005 27 50 80 225 1,030 153 Dates: 05-01 to 09-30

Total days 648

Table 4. Statistical summary of daily mean discharge by month for stream gage (15392000), Birch Creek above Twelvemile Creek near 

Miller House, Alaska, water years 2001–05. 

[Abbreviation: ft3/s, cubic foot per second]

Month

Discharge (ft3

/s) Number 

of 

observations 

Notes

Minimum 25th 

Percentile Median 75th 

Percentile Maximum

May 90 145 297 508 750 97 Includes estimated data 05-01 to 05-07-03, 05-01 

to 05-09-05; partial data 05-16 to 05-31-02, 

05-13 to 05-31-04; and no data for May 2001.

June 14 40 73 136 1,130 120 Includes estimated data 06-20 to 06-24-02 and 

06-29 to 06-30-05.

July 13 39 80 169 970 124 Includes estimated data 07-01 to 07-05-05.

August 13 32 44 96 395 128 Includes partial monthly data 08-28 to 08-31-01.

September 13 46 72 105 1,050 150 Includes estimated data 09-19 to 09-30-2004.

October 20 38 45 55 86 29 Includes partial monthly data 10-01 to 01-02-01; 

10-01 to 10-17-02; 10-01 to 10-10-03; and no 

data for 2004.

Total days 648

discharges recorded during open-water season for 2002, 

2003, and 2005 were comparable at approximately 1,000 ft3/s 

(table 3; fig. 4). The maximum daily mean discharge peak 

during the drought year of 2004 was 641 ft3/s (table 3), about 

35 percent less than other years. For the period of record, 

peak discharges of about 1,000 ft3/s occurred in June, July, 

and September. Minimum daily mean streamflows (~20 ft3/s 

or less) occurred during June, July, August, September, 

and October (table 4; fig. 5). A maximum instantaneous 

discharge of 2,100 ft3/s occurred July 27, 2003, from rainfall. 

Floodwaters over-topped the bank near the gage and flowed 

through heavily vegetated side channels behind the stream 

gage. An instantaneous discharge of 2,100 ft3/s was calculated 

indirectly using the slope-area method as described in 

Dalrymple and Benson (1967). Field data used for flood 

discharge calculations included channel cross sections 

surveyed downstream from the gage location, water-surface 

slope from flagged high-water marks, and a Manning’s 

streambed roughness coefficient (n value) of 0.040 determined 

from previous discharge measurements and observed channel 

characteristics. The roughness coefficient agrees with values 

for streams with similar morphology illustrated in Barnes 

(1967). 

Results 13
About 75 percent of the Birch Creek annual discharge, 

during 2002 through 2005, was at flows less than 200 ft3/s 

(fig. 4). Median streamflow ranged from 28 ft3/s in 2004 to 

108 ft3/s in 2002 (table 3). The statistical summary of daily 

mean discharge by month in table 4 and the boxplots of daily 

mean discharge by month (fig. 5) clearly illustrate the highly 

variable, precipitation-dependent, character of streamflow in 

the study area. Annual maximum and minimum discharges 

may occur during the same month.

The DGGS reported similar magnitude and variability 

in mean monthly streamflow and for instantaneous peak flow 

at the Birch Creek stream-gage site for 1986 through 1989. 

As an example, average monthly discharge for July 1987 

was 147 ft3/s; however, the July 1988 average discharge of 

35.4 ft3/s was substantially less than the previous year (Ray, 

1990). DGGS also reported that an instantaneous peak flow 

of 1,940 ft3/s occurred on June 25, 1989, with an estimated 

recurrence interval of 15 years (Ray, 1990). The magnitude 

of the calculated 1989 peak flow is similar to the maximum 

calculated instantaneous peak flow of 2,100 ft3

/s that occurred 

July 27, 2003, at the Birch Creek stream-gage site from a 

rainfall event. Except for the 2004 and 2005 summer drought 

periods, streamflow variability and magnitude in the upper 

Birch Creek watershed from 2001 through 2005 were similar 

to streamflow characteristics reported for the late 1980s. 

Crest-Stage Gages

Water-year and period-of-record peak flows for Harrison 

Creek and Frying Pan Creek crest-stage gages for 2002 

through 2005 were compiled in table 5. 

A water-year maximum discharge and period-of-record 

maximum discharge of 244 ft3/s for Upper Frying Pan 

Creek, site 15395900, occurred July 27, 2003, from rainfall. 

Discharge was calculated using the slope-area method 

(Dalrymple and Benson, 1967). The Manning’s streambed 

roughness coefficient (n value) selected was 0.038. The 

downstream gage on Frying Pan Creek (site 15396000) was 

installed in July 2004. A maximum flow of 10.6 ft3/s was 

measured August 3, 2004, during a field visit; however, no 

peak flows were recorded on the crest-stage gage during the 

2004 drought. A water-year maximum, and period-of-record 

maximum, for Frying Pan Creek of 171 ft3/s occurred May 30, 

2005. The peak probably was affected by channel ice.

The period-of-record maximum discharge of 199 ft3

/s 

for South Fork of Harrison Creek site 15407200 also occurred 

May 30, 2005, and may have been affected by channel ice as 

well. A discharge of similar magnitude, 184 ft3/s on July 27, 

2003, was calculated using the slope-area method (Dalrymple 

and Benson, 1967). Selected Manning’s roughness coefficients 

were 0.060 for the lower cross sections and 0.070 for the 

upstream section.

Table 5. Water-year and period-of-record maximum discharge for Harrison Creek and Frying Pan Creek 

crest-stage gages in the upper Birch Creek watershed near Central, Alaska, 2002–05. 

[Abbreviations: ft3/s, cubic foot per second; USGS, U.S. Geological Survey]

 USGS site 

identification

No. and name 

Water year

Event type

Period of record

Date

Maximum 

discharge

(ft3

/s)

Date

Maximum 

discharge 

(ft3/s)

15395900 Upper Frying Pan Creek 06-11-02 83 Rainfall

07-27-03 244 Rainfall; ice affected 07-27-03 244

05-24-04 90 Rainfall; ice affected

05-30-05 109 Rainfall; ice affected

15396000 Frying Pan Creek near 

Miller House

05-30-05 171 Rainfall; ice affected 05-30-05 171

15407200 South Fork Harrison 

Creek

07-27-03 184 Rainfall 

05-30-05 199 Rainfall 05-30-05 199

15407500 Harrison Creek 06-11-02 877 Rainfall

07-27-03 1,320 Rainfall 07-27-03 1,320

05-24-04 556 Rainfall; ice affected

05-30-05 492 Rainfall; ice affected

14  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
The Harrison Creek site 15407500 water-year maximum 

and period-of-record maximum discharge of 1,320 ft3/s 

occurred July 27, 2003, from a rainfall event. A discharge 

of similar magnitude, 913 ft3/s, was calculated from the 

September 2, 2003, peak using the slope-area method and a 

Manning’s roughness coefficient of 0.039.

Data were not adequate to develop peak flows by indirect 

methods or stage-discharge ratings for remote crest-gage sites 

on Volcano Creek site 15403000, Anvil Creek site 15404800, 

Great Unknown Creek sites 15397500 and 15397700, North 

Fork Twelvemile Creek site 15393900, and Ptarmigan Creek 

site 15389980. 

Stream Discharge Measurements

Stream discharge measurements collected during the 

project are available online at http://waterdata.usgs.gov/

nwis and associated daily mean discharge measurements 

were complied in appendix A (table A1). The discharge 

measurements were completed during open-water season. 

Most discharge measurements were obtained during low-flow 

conditions using a wading rod and current meter at measured 

discharges of 200 ft3

/s or less. Measured discharges at gage 

sites were compiled in table 6. During 2003, high-water marks 

were flagged on Birch Creek, Upper Frying Pan Creek, South 

Fork of Harrison Creek, and Harrison Creek. Associated 

discharges were calculated using channel cross-section survey 

data and indirect methods as outlined in (Dalrymple and 

Benson, 1967). The calculated instantaneous discharge for 

Birch Creek site 15392000 for July 27, 2003, was 2,100 ft3/s. 

The calculated indirect discharges for the same date were 

184 ft3/s for South Fork of Harrison Creek, site 15407200, 

1,320 ft3/s for Harrison Creek site 15407500, and 244 ft3/s for 

Upper Frying Pan Creek site 15395900.

Streamflow data from the Birch Creek stream gage, 

crest-gage data from Birch Creek tributaries, and discharge 

measurements at project stations can be used to estimate the 

magnitude and frequency of peak streamflows for ungaged 

sites on streams. Methods are outlined in Jones and Fahl 

(1994) and Curren and others (2003).

Water Quality 

Water-quality data were collected during 2004 and 2005 

for selected sites on Birch Creek, Frying Pan Creek, Harrison 

Creek, and South Fork of Harrison Creek. Data presented in 

this section cover four topics. First, data are presented for 

water-quality field parameters of pH, specific conductance, 

dissolved oxygen, and temperature collected during field 

visits. Water-chemistry data are covered for samples collected 

annually for major ions, nutrients, and alkalinity. Automated 

daily suspended-sediment concentration sample data for paired 

sites on Frying Pan Creek and Harrison Creek for selected 

periods, as well as miscellaneous suspended-sediment grab 

samples for selected sites are presented. Finally, this section 

presents data about mercury concentration in water samples 

collected during August and September 2005. These waterquality data provide quantitative information for assessing 

general environmental conditions as well as conditions for 

aquatic life.

Field Parameters 

 Water-quality field parameters of pH, specific 

conductance, dissolved oxygen, and temperature provide 

information on aquatic environmental conditions. The pH of 

water is a measure of its hydrogen-ion activity and can range 

from 0 (acidic) to 14 (alkaline) standard units. River water 

in areas not influenced by contaminants generally has a pH 

in the range 6.5 to 8.5 (Hem, 1985). Specific conductance 

is a measure of total dissolved solids. As ion concentrations 

increase, specific conductance of the solution increases. 

Higher forms of aquatic life require dissolved oxygen for 

survival. The equilibrium concentration of dissolved oxygen 

in water in contact with air is a function of temperature and 

pressure, and to a lesser degree, the concentration of other 

solutes (Hem, 1985). Water temperature is controlled by many 

factors.

Water-quality field parameters were measured at the 

Birch Creek stream gage site 15392000, at sites upstream and 

downstream from previously mined areas on Frying Pan Creek 

sites 15395900 and 15396000, as well as at South Fork of 

Harrison Creek site 15407200, Harrison Creek site 15407500, 

and several miscellaneous sites (table 6). Summary statistics 

for water-quality field parameters were compiled in table 7

and illustrated in figure 6.

Measured specific conductance for Birch Creek, Frying 

Pan Creek, and Harrison Creek sites ranged from a minimum 

52 μS/cm, during a June 1, 2005, Birch Creek peak flow 

precipitation/snowmelt event, to a maximum of 312 μS/cm at 

Frying Pan Creek on September 24, 2004, during low-flow 

conditions. Median specific conductance values ranged from 

96 μS/cm at South Fork Harrison Creek site 15407200 to 

197 μS/cm at Frying Pan Creek site 15396000 (table 7).

 The median specific conductance of 96 μS/cm for South 

Fork of Harrison Creek, site 15407200, was considerably 

lower than median values for other study sites. Mack and 

Moorman (1986) reported variation in specific conductance of 

25 to 193 μS/cm for samples collected in several Birch Creek 

tributaries. Lower conductance values were associated with 

precipitation events or were measured in basin headwaters 

where water residence time was short or bedrock was resistant 

to chemical weathering. 

Results 15
Table 6. Streamflow, water-quality field parameters, and suspended-sediment concentrations at selected sites in the upper Birch 

Creek watershed near Central, Alaska, 2003–05.

[Suspended sediment sampling method: EWI, equal width increment; E, estimated. Abbreviations: ft3/s, cubic foot per second; °C, degrees Celsius; μS/cm, 

microsiemens per centimeter at 25°C; mi, mile; mg/L, milligram per liter; <. less than; –, no data]

Date Time

 (hours)

Instantaneous 

steamflow

(ft3

/s)

Water 

temperature

 (°C)

Specific 

conductance 

at 25°C 

(μS/cm)

Dissolvedoxygen 

concentration 

(mg/L)

pH

(standard 

units)

Suspendedsediment

concentration 

(mg/L)

Suspendedsediment 

sampling method

15389980 (Ptarmigan Creek near mouth, near Central, Alaska)

07-22-03 1340 15.5 – – – – 1 Point

09-02-03 1711 236 – – – – 56 EWI

15392000 (Birch Creek above Twelvemile Creek, near Miller House, Alaska)

05-21-03 1515 161 – – – – 90 EWI

08-05-03 1235 246 – – – – 20 EWI

09-02-03 – 1,050 – – – – 1,386 Point 

06-09-04 1200 73.8 10.9 232 9.5 7.8 – –

06-18-04 1245 38.3 10.8 189 10.0 7.6 – –

07-09-04 1300 16.6 11.4 232 9.4 7.8 – –

08-24-04 1400 25.3 8.9 216 9.6 7.6 – –

09-01-04 1530 25.5 8.7 183 11.5 7.5 – –

06-01-05 1208 1,030 3.4 52 11.7 7.3 785 Point

06-13-05 1240 142 – – – – 17 EWI

06-27-05 1730 27.8 12.2 194 9.8 7.6 2 EWI

07-19-05 1844 200 12.4 125 7.3 7.5 – –

07-28-05 1130 64.3 13.2 168 7.9 7.7 – –

09-12-05 1730 60.0 7.9 187 10.2 7.6 – –

15393900 (North Fork Twelvemile Creek near Miller House, Alaska)

07-22-03 1235 6.54 – – – – 4 Point

09-02-03 1451 247 – – – – 83 EWI

15395900 (Upper Frying Pan Creek near Central, Alaska)

09-04-03 – – – – – – 26 EWI

06-10-04 1450 6.40 8.7 116 1

6.22 7.2 – –

08-03-04 1907 5.35 7.4 119 11.1 7.4 – –

09-01-04 1400 E 1.49 5.6 234 11.4 6.9 1 EWI

09-24-04 1640 0.70 1.0 312 11.6 7.6 <1 EWI

06-15-05 1330 2.96 9.9 156 9.5 7.2 1 EWI

06-25-05 1400 1.24 – – – – 1 EWI

07-19-05 1602 13.3 8.2 92 8.0 7.1 6 EWI

08-11-05 1736 2.04 10.8 214 9.9 7.2 1 EWI

09-04-05 1544 2.88 5.0 194 10.8 7.4 – –

09-13-05 1700 7.19 4.3 124 11.7 7.3 1 EWI

15396000 (Frying Pan Creek near Miller House, Alaska)

06-10-04 – – – – – – – –

08-03-04 1500 – 8.3 123 11.1 7.4 – –

09-01-04 1200 1.54 5.8 234 12.0 7.0 1 EWI

09-24-04 1323 1.05 1.8 312 12.0 7.4 1 EWI

06-15-05 1121 4.57 10.2 177 9.5 7.3 1 EWI

06-25-05 1250 1.93 – – – – <1 EWI

07-19-05 1228 27.90 7.5 97 8.2 7.1 10 EWI

08-11-05 1320 3.42 12.0 228 10.3 7.4 2 EWI

09-04-05 1659 4.60 6.2 216 10.8 7.6 – –

09-13-05 1547 13.00 4.6 142 11.9 7.3 2 EWI

15396100 (Frying Pan Creek at mouth, near Central, Alaska)

07-22-03 – – – – – – 4 Point

08-07-03 1250 23.70 – – – – 7 Point

09-18-03 1107 8.33 – – – – 3 Point

16  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Date Time

 (hours)

Instantaneous 

steamflow

(ft3

/s)

Water 

temperature

 (°C)

Specific 

conductance 

at 25°C 

(μS/cm)

Dissolvedoxygen 

concentration 

(mg/L)

pH

(standard 

units)

Suspended 

sediment

concentration 

(mg/L)

Suspended 

sediment 

sampling method

15397500 (Great Unknown Creek near Central, Alaska)

08-07-03 1515 28.10 – – – – 5 Point

09-17-03 1100 19.50 – – – – 2 Point

15397700 (East Fork Great Unknown Creek near Central, Alaska)

08-07-03 1420 31.30 – – – – 5 Point

09-17-03 1425 34.20 – – – – 2 Point

15407200 (South Fork Harrison Creek near Central, Alaska)

08-06-03 1438 35.80 – – – – 1 Point

09-05-03 1550 41.20 – – – – 3 EWI

07-08-04 1230 1.72 10.4 96 9.4 7.4 – –

07-31-04 1510 – 9.9 95 10.2 7.5 1 Point

08-31-04 1350 1.57 7.5 110 11.9 7.2 <1 EWI

09-27-04 1354 2.14 0.4 113 14.7 7.2 <1 EWI

06-15-05 1753 5.98 11.0 84 9.2 7.4 5 EWI

06-27-05 1255 4.58 9.5 98 10.6 7.4 1 EWI

07-20-05 1245 11.70 8.6 76 10.1 7.4 <1 EWI

08-14-05 1855 5.02 11.6 96 10.7 7.3 1 EWI

08-18-05 1500 5.05 7.6 105 10.6 7.4 1 EWI

09-27-05 1340 24.00 2.6 66 12.4 7.3 <1 EWI

15407500 (Harrison Creek above Bottom Dollar Creek, near Central, Alaska)

09-03-03 1515.00 411 – – – – 67 EWI

06-17-04 1152 33.50 15.0 152 9.1 7.8 – –

08-05-04 1155 18.11 15.9 216 9.7 7.9 – –

08-30-04 1215 12.06 9.0 218 11.7 7.5 <1 Point

09-19-04 1410 9.83 4.4 221 13.7 7.7 <1 EWI

06-13-05 1725 46.2 17.8 – – – 2 EWI

06-28-05 1351 20.7 15.8 186 9.5 7.8 1 EWI

07-20-05 1944 2

80-126 E 11.4 112 9.4 7.7 – –

08-12-05 1451 36.2 14.0 191 9.7 7.9 1 EWI

08-17-05 1400 35.2 11.3 179 10.5 7.8 1 EWI

09-12-05 1455 53 7.4 176 11.5 7.7 1 EWI

Miscellaneous 2005 sample sites on Harrison Creek

652149145074900 (North Fork Harrison Creek 0.1 mi above mouth, near Central, Alaska)

08-18-05 1820 12.60 9.0 197 10.6 7.9 – –

652129145001700 (Harrison Creek 0.4 mi above Ptarmigan Gulch, near Central, Alaska)

08-31-05 1600 32.50 9.0 174 11.1 7.9 – –

652132144593900 (Ptarmigan Gulch 0.2 mi above mouth, near Central, Alaska)

08-31-05 1500 3

<2 E 6.9 173 11.7 7.8 – Center flow point

652209144573700 (Harrison Creek 1.3 mi below Ptarmigan Gulch, near Central, Alaska)

08-31-05 1400 31.00 9.5 179 10.9 7.9 – –

652231144541200 (Harrison Creek 0.2 mi above Squaw Creek, near Central, Alaska)

08-17-05 1900 29.50 11.7 171 10.0 7.8 – –

1

Dissolved oxygen data suspect; no calibration in log book. Not used in summary statistics.

2

Streamflow estimated at 80–126 ft3/s. Used 103 ft3/s as best estimate in table 7 summary statistics.

3

Grab water sample for total mercury, discharge estimated at less than 2 ft3/s, water-quality field parameters recorded: No sediment sample.

Results 17

Table 6. Streamflow, water-quality field parameters, and suspended-sediment concentrations at selected sites in the upper Birch 

Creek watershed near Central, Alaska, 2003–05.—Continued

[Suspended sediment sampling method: EWI, equal width increment; E, estimated. Abbreviations: ft3/s, cubic foot per second; °C, degrees Celsius; μS/cm, 

microsiemens per centimeter at 25°C; mi, mile; mg/L, milligram per liter; <. less than; –, no data]
AK19-5003_Fig06

15392000 15395900 15396000 15407200 15407500

STATION

6.8

7.0

7.2

7.4

7.6

7.8

8.0

PH, IN STANDARD UNITS

15392000 15395900 15396000 15407200 15407500

STATION

6

8

10

12

14

16

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

0

100

200

300

350

250

150

50

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER 

CENTIMETER AT 25 DEGREES CELSIUS

0

5

10

15

20

TEMPERATURE, IN DEGREES CELSIUS

A. B.

C. D.

10 9 8 10 10 10 9 8 10 9

10 8 8 10 9 10 9 8 10 9

10 Number of observations

100th percentile

75th percentile

Median

25th percentile

0 percentile

EXPLANATION

Figure 6. Distribution of water-quality field parameters for selected sites in the upper Birch Creek watershed near Central, 

Alaska, 2004 and 2005. (A) water temperature, in degrees Celsius, (B) specific conductance, in microsiemens per centimeter at 

25 degrees Celsius, (C) dissolved oxygen, in milligrams per liter, and (D) pH, in standard units.

During open-water season, water temperatures are 

influenced by diurnal air temperature fluctuations. Summer 

diurnal water temperatures varied by 4 to 8°C. Higher 

water temperatures occurred in late afternoon to early 

evening. A maximum water temperature of 17.8°C was 

measured at Harrison Creek site 15407500 during summer 

low-flow conditions on June 13, 2005, in early evening. 

Water temperatures were near 0°C during spring May–June 

snowmelt and in late September as ice formed in stream 

channels. Median water temperatures during open-water 

season were between 7.4°C and 12.7°C (table 7). 

Measured dissolved-oxygen concentrations ranged 

from 7.3 to 14.7 mg/L (table 7). Seasonal maximums were 

in late summer or early autumn, coincident with colder water 

temperatures, or during spring snowmelt and runoff. Median 

dissolved-oxygen concentrations for Birch Creek, Frying Pan 

Creek, and Harrison Creek ranged from 9.7 to 11.0 mg/L. 

(table 7). Brabets and others, (2000), reported a similar mean 

dissolved-oxygen concentration of 10.3 mg/L for interior 

highland streams of the Yukon basin. 

Dissolved-oxygen concentrations measured at selected 

sample sites in the Birch Creek watershed were near 

equilibrium concentrations (U.S. Geological Survey, 1998) for 

the range of water temperatures, atmospheric pressures, and 

conductivities measured at sample sites. Hence, dissolvedoxygen concentrations at the Birch Creek study sites were not 

substantially depleted by processes that consume dissolved 

oxygen.

Measured pH was near neutral to moderately alkaline 

(6.9 to 7.9) (table 7). Median pH values for Birch Creek, 

Frying Pan Creek, and Harrison Creek, ranged from 7.2 to 7.8 

standard units (table 7). The median pH for Upper Frying Pan 

Creek site 15395900 was 7.2. The median pH for Harrison 

Creek site 15407500 was 7.8. Bjerlkie and LaPerriere (1985) 

18  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Table 7. Statistical summary of water-quality field parameters at selected sites in the upper Birch Creek watershed near Central, 

Alaska, 2004 and 2005.

[Abbreviations: ft3/s, cubic foot per second; μS/cm, microsiemens per centimeter at 25°C; °C, degrees Celsius; mg/L, milligram per liter; USGS, U.S. 

Geological Survey]

USGS site 

identification 

No.

Site name Constituent or property Minimum 25th 

percentile Median 75th 

pecentile Maximum Number of samples

15392000 Birch Creek above 

Twelvemile Creek, near 

Miller House, Alaska

Discharge, instantaneous 

(ft3

/s)

16.6 30.4 69.1 190 1,050 14

Water temperature °C 3.4 8.8 10.8 12.0 13.2 10

Specific conductance 

(μS/cm at 25°C)

52 172 188 211 232 10

Dissolved oxygen (mg/L) 7.3 9.4 9.7 10.1 11.7 10

pH, field (standard units) 7.3 7.5 7.6 7.7 7.8 10

15395900 Upper Frying Pan Creek 

near Central, Alaska

Discharge, instantaneous 

(ft3

/s)

.70 1.63 2.92 6.14 13.3 10

Water temperature °C 1.0 5.0 7.4 8.7 10.8 9

Specific conductance 

(μS/cm at 25°C)

92 119 156 214 312 9

Dissolved oxygen (mg/L) 8.0 9.8 10.9 11.5 11.7 8

pH, field (standard units) 6.9 7.2 7.2 7.4 7.6 9

15396000 Frying Pan Creek near 

Miller House, Alaska

Discharge, instantaneous 

(ft3

/s)

1.10 1.83 4.00 6.70 27.9 8

Water temperature °C 1.8 5.5 6.9 8.7 12.0 8

Specific conductance 

(μS/cm at 25°C)

97 137 197 230 312 8

Dissolved oxygen (mg/L) 8.2 10.1 11.0 11.9 12.0 8

pH, field (standard units) 7.0 7.2 7.3 7.4 7.6 8

15407200 South Fork Harrison Creek 

near Central, Alaska

Discharge, instantaneous 

(ft3

/s)

1.57 3.36 5.05 17.9 41.2 11

Water temperature °C .4 7.5 9.0 10.3 11.6 10

Specific conductance 

(μS/cm at 25°C)

66 87 96 103 113 10

Dissolved oxygen (mg/L) 9.2 10.1 10.6 11.6 14.7 10

pH, field (standard units) 7.2 7.3 7.4 7.4 7.5 10

15407500 Harrison Creek above 

Bottom Dollar Creek, 

near Central, Alaska

1

Discharge, instantaneous 

(ft3

/s)

9.80 19.4 35.2 49.6 411 11

Water temperature °C 4.4 9.6 12.7 15.6 17.8 10

Specific conductance 

(μS/cm at 25°C)

112 176 186 216 221 9

Dissolved oxygen (mg/L) 9.1 9.5 9.7 11.5 13.7 9

pH, field (standard units) 7.5 7.7 7.8 7.8 7.9 9

1

 Includes 07-20-05 estimated discharge of 103 ft3/s.

reported pH values of 6.6 to 7.8 for sites measured on Birch 

Creek, Twelvemile Creek, and Ptarmigan Creek. The pH 

range of 6.9 to 7.9 measured during the Birch Creek study 

are consistent with the near neutral to moderately alkaline pH 

values measured in mined and unmined streams in the upper 

Birch Creek watershed by the DGGS during 1984 (Mack and 

Moorman, 1986).

Generally, relatively low specific conductance and 

pH values were associated with peak flows. Higher water 

temperatures were associated with lower dissolved-oxygen 

levels. Discharge and specific conductance and discharge and 

pH were inversely related. Water-quality field parameters 

provide information on the aquatic environmental conditions. 

Changes in these characteristics along a stream reach or over 

time can help identify degraded habitat.

Results 19
Major Ions

Major-ion compositions commonly vary temporally 

with changes in flow conditions, spatially with changes in 

geomorphic and geologic conditions, and with inputs from 

tributaries. Samples were collected at Harrison Creek sites 

15407200 and 15407500, and at Frying Pan Creek sites 

15395900 and 15396000, during late summer 2004, low-flow 

conditions. Samples were collected at the same sites during 

2005 low-flow conditions, as well as at Birch Creek site 

15392000 and two miscellaneous sites, 652129145001700, 

and 652209144573700, on Harrison Creek (fig. 2; table 8). 

The miscellaneous sites were located at the upstream and 

downstream margin of an area severely disturbed by mining. 

The area was scheduled for reclamation work during 2006. 

Cation composition primarily was mixed calciummagnesium with calcium predominant for all samples; anion 

compositions were mixed sulfate and bicarbonate or sulfate 

with minor bicarbonate for Frying Pan Creek and bicarbonate 

with minor sulfate for Birch Creek and Harrison Creek (fig. 7). 

Cation and anion compositions are similar to those reported 

by Brabets and others (2000). They determined the Yukon 

River tributaries were predominantly calcium-magnesiumbicarbonate waters with specific conductance ranging from 54 

to 373 μS/cm. 

Major-ion concentrations typically were greater for 

samples collected during the extended drought in 2004 than 

for samples collected during 2005 (table 8). Concentrations 

of major ions in water samples collected at Birch Creek site 

15392000 during September 2005 were of similar magnitude 

as samples collected at study sites on Frying Pan Creek and 

Harrison Creek (fig. 8).

Nutrients

Nutrients were sampled at Harrison Creek sites 15407200 

and 15407500 and at Frying Pan Creek sites 15395900 and 

15396000 during late summer 2004, low-flow conditions. 

Samples were collected at the same sites during 2005 low-flow 

conditions, as well as at Birch Creek site 15392000 and two 

miscellaneous sites on Harrison Creek. Nutrient data were 

compiled and summarized in table 9. 

Compounds of nitrogen and phosphorus are referred 

to as macronutrients because they are needed in relatively 

high concentrations for plant growth. In excess quantities, 

macronutrients can promote nuisance algae growth in streams 

and lakes causing eutrophication. Natural sources of nutrients 

include precipitation, rock weathering, and biochemical 

processes such as decomposition of organic matter.

Table 8. Summary of major-ion concentrations at selected sites in the upper Birch Creek watershed near Central, Alaska, 2004 and 

2005.

[Concentrations are dissolved and in milligrams per liter unless otherwise noted. Abbreviations: USGS NWIS, U.S. Geological Survey National Water 

Information System; μg/L, microgram per liter; E, estimated; <, less than; –, no data]

USGS site 

identification 

No.

Sample 

date

Sample 

time 

(hours)

Constituent (USGS NWIS code)

Calcium 

(00915)

Magnesium 

(00925)

Sodium 

(00930)

Potassium 

(00935)

Chloride 

(00940)

Sulfate 

(00945)

Fluoride 

(00940)

Silica 

(00955)

Iron 

(01046) 

(μg/L) 

Manganese 

(01056) 

(μg/L) 

15392000 09-12-05 1730 24.9 8.21 0.89 0.69 E0.11 28.2 E0.05 5.10 19.0 11.0

15395900 09-01-04 1400 32.5 15.3 1.84 .61 <0.20 90.3 <.17 6.37 46.8 10.2

09-04-05 1330 17.9 7.36 1.01 .34 <.20 48.0 <.10 5.03 54.0 7.30

15396000 09-01-04 1200 34.0 15.7 1.60 .65 <.20 81.1 <.17 6.03 24.7 248

09-04-05 1630 25.2 11.4 1.16 .43 <.20 50.8 <.10 6.12 43.0 101

15407200 08-31-04 1500 19.5 1.94 .76 .53 E.14 11.8 <.17 5.96 <6.40 <.8

08-18-05 1620 14.8 1.35 .74 .48 <.20 11.0 E.06 4.64 <6.00 .80

15407500 08-30-04 1300 37.2 6.07 1.24 .92 .27 37.5 <.17 5.24 E4.80 9.80

08-17-05 1600 30.4 4.95 1.10 .87 <.20 27.0 <.10 5.48 12.0 5.70

652129145001700 08-31-05 1600 24.9 4.29 .86 .76 <.20 22.2 <.10 4.60 19.0 7.00

652209144573700 08-31-05 1400 25.2 4.34 .77 .75 <.20 24.2 <.10 4.85 16.0 15.0

Minimum 14.8 1.35 0.74 0.34 <0.20 11 <0.10 4.6 <6 <0.8

Maximum 37.2 15.7 1.84 .92 .27 90.3 <.17 6.37 54 248

Median 25.2 6.07 1.01 .65 – 28.2 – 5.24 – 10.0

20 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Nutrient samples for this study were collected during 

low-flow conditions. Concentrations of macronutrients 

nitrogen and phosphorus were low, less than 0.3 mg/L 

(table 9). Total phosphorus concentrations typically were less 

than 0.004 mg/L, except for a concentration of 0.009 mg/L 

from sample site 15392000 (table 9). Median concentration of 

dissolved nitrite plus nitrate was 0.115 mg/L. The maximum 

concentration of dissolved nitrite plus nitrate was 0.218 mg/L. 

Brabets and others (2000) reported nitrogen and phosphorus 

concentrations of similar magnitude for the main stem of 

the Yukon River and Interior tributaries. Streams that drain 

mountainous terrain with poorly developed soils typically have 

low nutrient concentrations.

Mercury 

Filtered and unfiltered water samples were collected 

for analysis of mercury concentration at 10 sites during 

August and September 2005 because of concerns about 

possible mercury contamination associated with abandoned 

placer-gold-mine operations. Mercury concentrations were 

summarized in table 10 for one site on Birch Creek, two sites 

on Frying Pan Creek, six sites on Harrison Creek, and one site 

on Ptarmigan Gulch (fig. 2). Total-recoverable (unfiltered) 

concentrations and dissolved (filtered) concentrations were 

low, less than 0.01 μg/L at all sites, indicating the particulatephase (greater than 0.45 μm) mercury concentrations were 

not substantial. All 2005 mercury samples collected were at 

Figure 7. Major-ion composition of samples at selected sites in the upper Birch Creek watershed near 

Central, Alaska, 2004 and 2005.

AK19-5003_Fig07

 0

 20

 40

 60

 80

 100

SULFATE PLUS CHLORIDE

 0

 20

 40

 60

 80

 100

CALCIUM PLUS MAGNESIUM

 100

 80

 60

 40

 20

 0

 100

 80

 60

 40

 20

 0

PERCENT

CHLORIDE, FLUORIDE, NITRITE PLUS NITRATE

 0

 20

 40

 60

 80

 100

 100

 80

 60

 40

 20

 0

CARBONATE PLUS BICARBONATE

 100

 80

 60

 40

 20

 0

SULFATE

PERCENT

PERCENT

CALCIUM

 100

 80

 60

 40

 20

 0

 0

 20

 40

 60

 80

 100

MAGNESIUM

 0

 20

 40

 60

 80

 100

SODIUM PLUS POTASSIUM

EXPLANATION

15392000 Birch Creek above Twelvemile Creek

15395900 Upper Frying Pan Creek

15396000 Frying Pan Creek

15407200 South Fork Harrison Creek

15407500 Harrison Creek

Results 21
AK19-5003_Fig08

 0

 20

 40

 60

 80

 100

SULFATE PLUS CHLORIDE

 0

 20

 40

 60

 80

 100

CALCIUM PLUS MAGNESIUM

 100

 80

 60

 40

 20

 0

 100

 80

 60

 40

 20

 0

PERCENT

CHLORIDE, FLUORIDE, NITRITE PLUS NITRATE

 0

 20

 40

 60

 80

 100

 100

 80

 60

 40

 20

 0

CARBONATE PLUS BICARBONATE

 100

 80

 60

 40

 20

 0

SULFATE

PERCENT

PERCENT

CALCIUM

 100

 80

 60

 40

 20

 0

 0

 20

 40

 60

 80

 100

MAGNESIUM

 0

 20

 40

 60

 80

 100

SODIUM PLUS POTASSIUM

EXPLANATION

Harrison Creek Basin—Sites 15407200 and 

15407500

Frying Pan Creek Basin—Sites 15395900 and 

15396000

Birch Creek Basin—Site 15392000

Figure 8. Major-ion composition of samples at selected sites by drainage basin in the upper Birch Creek 

watershed near Central, Alaska, 2004 and 2005.

concentrations less than the 2.0 μg/L maximum drinking water 

mercury contaminant level set by ADEC (Alaska Department 

of Environmental Conservation, 2003) and the National 

Primary Drinking Water Regulations (U.S. Environmental 

Protection Agency, 2003). Mack and Moorman (1986) 

investigated mercury concentration in water samples from 

several sites in the Birch Creek basin. Their results showed 

slightly elevated mercury concentrations of 6 μg/L or less. 

Mack and Moorman suggested their results may indicate 

naturally elevated mercury concentrations in mined as well as 

unmined areas, or the elevated values may represent analytical 

error rather than actual anomalies.

Suspended Sediment

For selected periods during the 2004 and 2005 field 

seasons, daily suspended-sediment samples were collected 

using automated samplers. The samples were used to 

document variations in suspended-sediment concentration 

at sites upstream and downstream from previously mined 

areas on Harrison Creek and Frying Pan Creek (table A1). 

Automated samplers collected daily samples at South Fork of 

Upper Frying Pan Creek site 15395900, and Frying Pan Creek 

site 15396000, Harrison Creek site 15407200, Harrison Creek 

site 15407500. 

22 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Table 9. Summary of nutrient concentrations at selected sites in the upper Birch Creek watershed near Central, Alaska, 2004 and 2005.

[Concentrations are dissolved and in milligrams per liter unless otherwise noted. Abbreviations: USGS NWIS, U.S. Geological Survey National Water 

Information System; μg/L, microgram per liter; E, estimated; <, less than; –, no data]

USGS site

identification 

No.

Sample 

date

Sample 

time 

(hours)

Constituent (USGS NWIS code)

Phosphorus, 

total 

(00665)

Phosphorus 

(00666)

Orthophosphate 

phosphorus 

(00671)

Nitrate, 

as N 

(00613)

Nitrite-plusnitrate, as N 

(00631)

Ammonia, 

as N 

(00608)

Ammonia plus 

organic, as N 

(00623)

Ammonia plus 

organic, 

as N, total 

(00625)

15392000 09-12-05 1730 0.009 0.01 <0.006 <0.002 0.110 <0.010 0.2 0.1

15395900 09-01-04 1400 E.002 <.004 <.006 E.001 .087 E.006 .2 .2

09-04-05 1330 <.004 E.003 <.006 <.002 .104 E.006 .3 .3

15396000 09-01-04 1200 E.003 E.002 <.006 E.001 .115 .017 .2 .2

09-04-05 1630 E.003 E.003 <.006 <.002 .113 E.009 .3 .2

15407200 08-31-04 1500 <.004 <.004 <.006 <.002 .098 <.010 <.1 <.1

08-18-05 1620 <.004 <.004 <.006 .038 .133 <.010 <.1 E.06

15407500 08-30-04 1300 <.004 <.004 <.006 .002 .142 <.010 E.08 E.07

08-17-05 1600 <.004 E.003 <.006 .002 .218 E.005 .1 .1

652129145001700 08-31-05 1600 .004 E.002 <.006 E.001 .185 <.010 .1 .1

652209144573700 08-31-05 1400 E.003 <.004 <.006 E.001 .205 <.010 .1 .1

Minimum E0.002 E0.002 <0.006 <0.002 0.087 <0.010 <0.1 <0.1

Maximum .009 .01 <.006 .038 .218 .017 .3 .3

Median – – – – .115 – – –

Table 10. Summary of mercury concentrations in water and streambed sediment at selected sites in the upper Birch Creek 

watershed near Central, Alaska, 2005.

[Abbreviations: USGS NWIS, U.S. Geological Survey National Water Information System; μg/L, microgram per liter; μg/g, microgram per gram; 

E, estimated; <, less than; –, no data]

USGS site

identification 

No.

Sample date Sample time 

(hours)

Mercury (USGS NWIS code)

Water, 

filtered 

(71890) 

(μg/L)

Water, 

unfiltered 

(71900) 

(μg/L)

Bed material, 

sieved 

(34910)

(μg/g)

Bed material, 

sieved

(replicate)

(μg/g)

15392000 09-12-05 1730 <0.01 <0.01 – 0.05

15395900 09-04-05 1330 <.01 <.01 0.06 .03

15396000 09-04-05 1630 <.01 <.01 .05 .04

15407200 08-18-05 1620 <.01 <.01 .04 .04

15407500 08-17-05 1600 <.01 <.01 .05 .03

652149145074900 08-18-05 1820 <.01 <.01 .04 .03

652129145001700 08-31-05 1600 <.01 <.01 .03 .04

652132144593900 08-31-05 1500 <.01 <.01 – –

652209144573700 08-31-05 1400 <.01 <.01 .04 .03

652231144541200 08-17-05 1900 <.01 <.01 .05 .03

Minimum <0.01 <0.01 0.03 0.03

Maximum <.01 <.01 .06 .05

Median <.01 <.01 .05 .03

Results 23
Median suspended-sediment concentrations were less 

than 5 mg/L for the upstream and downstream Frying Pan 

Creek sites. Median sediment concentration was less than 

15 mg/L for upstream and downstream sites on Harrison Creek 

(table 11). The maximum suspended-sediment concentrations 

collected using automated samplers on Frying Pan Creek and 

Harrison Creek were 816 and 290 mg/L, respectively. 

Median suspended-sediment concentrations for the 115 

paired samples from Frying Pan Creek and 101 paired samples 

from Harrison Creek were less than the 20 mg/L TMDL set 

by the U.S. Environmental Protection Agency (1996) for the 

upper Birch Creek basin (table 11; fig. 9). It is important to 

emphasize, however, that suspended-sediment paired samples 

were collected primarily during low-flow conditions. The 

U.S. Environmental Protection Agency (1996) reported that 

during low-flow conditions, the upper Birch Creek watershed 

generally met the turbidity criterion. They also reported most 

of the sediment load transported by the streams occurred 

over a short period—84 percent of the total sediment load 

for their 1993 study was transported in 1 day for Birch Creek 

at Twelvemile Creek. Similarly, Vohden (1999) concluded 

that rainfall events played a major role in explaining elevated 

suspended-sediment concentration values recorded at 

monitoring locations operated by the Alaska Department 

of Natural Resources (ADNR) on Birch Creek. Suspendedsediment paired-sample data collected during 2004 and 2005 

summer drought conditions did not include high-flow samples. 

Hence, these data were not representative of associated high 

suspended-sediment concentrations that periodically occur in 

the watershed during a typical summer season.

Table 11. Statistical summary of daily suspended-sediment concentrations at selected sites in Frying Pan Creek and 

Harrison Creek near Central, Alaska, water years 2004 and 2005.

[Concentrations are in milligrams per liter. Abbreviations: <, less than]

USGS site 

identification 

No.

Site name

Number of 

paired sediment 

samples

Minimum 25th 

percentile Median 75th 

percentile Maximum

15395900 Upper Frying Pan Creek near 

Central, Alaska

115 1 1 2 4 107

15396000 Frying Pan Creek near Miller 

House, Alaska

115 <1 2 3 6 816

15407200 South Fork Harrison Creek near 

Central, Alaska

101 <1 1 1 2 158

15407500 Harrison Creek above Bottom 

Dollar Creek near Central, 

Alaska

101 1 4 7 14 290

Miscellaneous suspended-sediment samples were 

collected at selected sites on Birch Creek and several 

tributaries during 2003 through 2005 (table 6). Maximum 

recorded suspended-sediment concentration for miscellaneous 

grab samples collected during high water was 1,386 mg/L at 

Birch Creek station 15392000, on September 2, 2003 (table 6). 

Minimum suspended-sediment concentrations for several sites 

were less than 1 mg/L. 

Suspended-sediment concentration generally increased 

with increased streamflow (tables 6 and A1). Sediment 

concentrations typically were higher at downstream sites 

than at upstream sites (table 11). There were, however, 

several elevated suspended-sediment concentrations in the 

2004 through 2005 sediment record that were not associated 

with precipitation. Suspended-sediment samples collected at 

Harrison Creek on September 10, 2004, provide one example 

of an anomalous suspended-sediment concentration that may 

result from a localized in-stream disturbance. Suspendedsediment concentrations at the Harrison Creek downstream 

site (15407500) usually were greater than concentrations 

at the Harrison Creek upstream site (15407200). However, 

September 10, 2004, data show a sediment concentration of 

158 mg/L at the upstream site (15407200) and only 13 mg/L at 

the downstream site (15407500) with no precipitation recorded 

at local climate stations (table A1). 

Several factors may have had an adverse affect on the 

magnitude of suspended-sediment concentration in samples 

collected with automated samplers on Harrison Creek and 

Frying Pan Creek: (1) Access to Harrison Creek and Frying 

Pan Creek primarily was on established ATV trails that, at 

24  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
times, were used heavily by the public. Occasionally, ATVs 

were observed traveling in Harrison Creek and Frying Pan 

Creek upstream from automated sampler sites; (2) Localized 

heavy precipitation during the summer may affect suspendedsediment concentration at only one gage site in a particular 

basin. For example, table A1 shows more than 0.5 in. of 

precipitation recorded at Circle and Central on August 2, 

2005, but only a trace at Birch Creek and none at Eagle 

Summit; (3) High suspended-sediment loads were observed 

for about 2 hours after collapse of a cut-bank upstream from 

Harrison Creek site 15407500; (4) Wildlife was active in 

the study area, and on occasion, likely disturbed fine-grain 

sediments upstream from sites, during or shortly before, 

collection of automated samples. 

Suspended-sediment data collected using automated 

samplers, as well as concurrent daily precipitation and 

daily mean discharge recorded at Birch Creek station 

15392000, were summarized in table A1 in appendix A. 

Daily precipitation recorded at nearby climate stations at 

Central, Circle Hot Springs, Eagle Summit, Mount Ryan, and 

Monument Creek at Chena Hot Springs (fig. 1) also were 

summarized in table A1 to facilitate comparison between daily 

suspended-sediment data and daily precipitation records from 

nearby climate stations. 

Trace Elements in Streambed Sediment

Analysis of trace elements in streambed-sediment 

samples provides a reliable means for assessing the 

occurrence, concentration, and distribution of trace elements 

in an aquatic system. Most trace elements and many 

anthropogenic organic compounds are known to associate 

with fine-grained sediments (Van Metre and Callender, 1997). 

AK19-5003_Fig09

101

102

10-1

100

SUSPENDED SEDIMENT CONCENTRATION, 

IN MILLIGRAMS PER LITER

15395900 15396000 15407200 15407500

STATION

115 115 101 101

101 Number of observations

100th percentile

75th percentile

Median

25th percentile

0 percentile

EXPLANATION

Figure 9. Distribution of daily suspended-sediment 

concentration data from automated samplers for selected 

sites in Frying Pan Creek and Harrison Creek near Central, 

Alaska, 2004 and 2005. (Values less than 1 milligram per 

liter are not shown.)

Consequently, even though the water may contain only small 

quantities of these constituents, suspended sediment and bed 

sediment may contain relatively large concentrations (Shelton 

and Capel, 1994). Accordingly, sampling and analysis of 

streambed-sediment material increases the likelihood that 

contaminants will be detected and that spatial distribution of 

trace elements in the aquatic environment can be evaluated.

Trace-Element Aquatic-Life Criteria

There are no official Federal or State of Alaska standards 

for trace-element concentrations in freshwater streambed 

sediments. However, sediment-quality guidelines (SQG) for 

a select number of elements have been proposed by several 

agencies and organizations to assess potential effects of 

sediment contamination on aquatic life. MacDonald and 

others (2000) compiled SQG and data from several sources 

and developed consensus-based probable effect concentration 

(CB-PECs) guidelines for freshwater ecosystems. Gilliom 

and others (1998) summarized aquatic-life criteria from 

various agencies and compiled National median values based 

on streambed-sediment data collected at 198 nonrandom 

sites by the USGS NAWQA program. Aquatic-life criteria 

and National data sets are useful for comparison purposes. 

They provide perspective for evaluation of the streambedsediment data, but should be used only as indicators of 

potential sediment-quality problems that may warrant further 

examination. Alternatively, the absence of criteria for a 

particular contaminant, or the presence of contaminants that 

do not exceed one or more criteria, does not imply necessarily 

that there are no environmental issues of concern at that 

site. Mixtures of contaminants at some sites could behave 

synergistically to cause adverse biological effects that are not 

indicated by criteria developed for individual contaminants 

(U.S. Geological Survey, 1998). Elevated concentrations of 

trace elements in sediment may represent enrichment from 

natural or anthropogenic sources. 

Selected Trace Elements

Streambed-sediment samples were collected during lowflow conditions at nine sites (fig. 2) in August and September 

2005 because of concerns about elevated levels of heavy-metal 

contaminants, such as mercury, lead, and zinc, that may be 

associated with abandoned placer-mine operations. Because 

natural background levels for a particular contaminant may 

change substantially with changes in sediment-source geology, 

a suite of 40 trace elements were selected for analysis to 

document between-site variations in sediment constituents. 

Table 2 presents the list of trace elements, methods, reporting 

units, and minimum reporting limits.

Streambed-sediment samples were collected in Harrison 

Creek at the upstream site 15407200, at the downstream 

site 15407500, and at four intermediary sites in mined 

areas scheduled for reclamation work in 2006 (fig. 2). 

Results 25
Additional sediment samples were collected from 

Birch Creek site 15392000 and Frying Pan Creek 

sites 15395900 and 15396000 to document traceelement background levels in the study area. 

Trace-element analytical results were 

compiled in appendix A (table A2). Statistical 

summaries of trace-element concentrations in 

streambed sediment were compiled in table 12. 

Streambed-sediment-quality guidelines for 

nine U.S. Environmental Protection Agency 

(1994) priority pollutants—arsenic, cadmium, 

chromium, copper, lead, mercury, nickel, 

selenium, and zinc—were compared with 

trace-element concentrations for streambedsediment samples collected from selected sites 

in table 13. Trace-element concentrations were 

not normalized for organic carbon content in 

the streambed sediments for comparison with 

sediment-quality guidelines. Organic carbon 

content was less than 5 percent for all samples 

(table A2). Median concentrations of mercury, 

lead, and zinc for all samples were less than 

the NAWQA National median concentrations 

compiled by Gilliom and others (1998) and less 

than the CB-PEC summarized by MacDonald 

and others (2000) (table 13). Averaged mercury 

concentrations ranged from 0.03 to 0.05 μg/g, 

lead concentrations ranged from 19.7 to 24 μg/g, 

and zinc concentrations ranged from 83.6 to 

119 μg/g (table 12).

Median concentrations of arsenic, 

chromium, and nickel were greater than the 

NAWQA National median and several sample 

concentrations exceeded the CB-PEC (table 13). 

Arsenic concentrations ranged from 12 to 

60 μg/g, chromium values varied from 49 

to 55 μg/g, and nickel concentrations were 

11.9 to 71.7 μg/g (table 12). Elevated arsenic 

concentrations in streambed sediment were 

expected because significant concentrations 

of arsenic are present in local bedrock (Foster 

and others, 1994; Newberry, 1996). Elevated 

chromium and nickel likely were associated with 

sediment input from weathered mafic-igneous 

rocks noted by Yeend (1991) and Foster and 

others (1994). Histograms showing streambedsediment concentrations for selected sites in the 

upper Birch Creek watershed for the nine U.S. 

Environmental Protection Agency (1994) priority 

pollutants (table 13) and CB-PEC were compiled 

in figure 10.

Figure 10. Histogram plots for nine priority-pollutant trace elements in selected 

streambed-sediment samples from the upper Birch Creek watershed near 

Central, Alaska, 2005. (CB-PEC, consensus based probable effect concentration 

[MacDonald and others, 2000]; μg/g, microgram per gram; NG, no guideline.)

AK19-5003_Fig10

Arsenic

0

70 Frying Pan Creek Harrison Creek

Cadmium

0

0.7

CONCENTRATION, IN MICROGRAMS PER GRAM

Chromium

0

20

40

60

80

100

120

140

160

15392000

 15395900

15396000

 15407200

652149145074900

65129145001700

652209144573700652231144541200

15407500

Mercury

0

0.06

0

10

20

30

Lead

Copper

0

20

40

60

80

100

Nickel

0

20

40

60

80

100

Selenium

0

0.6

Zinc

0

20

40

60

80

100

120

Birch

Creek

SITE NUMBER

CB-PEC = 33 μg/g

CB-PEC = 111 μg/g

CB-PEC = 1.06 μg/g

CB-PEC = 459 μg/g

CB-PEC = NG

CB-PEC = 48.6 μg/g

CB-PEC = 128 μg/g

CB-PEC = 4.98 μg/g

CB-PEC = 149 μg/g

26  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Table 12. Statistical summary of trace-element concentrations in streambed sediment at selected sites in the upper Birch Creek 

watershed near Central, Alaska, 2005.

[Concentrations are in milligrams per gram unless otherwise indicated. Abbreviation: <, less than]

Constituent Minimum 25th 

percentile Median 75th 

percentile Maximum Number of samples

Mercury1 0.03 0.03 0.03 0.04 0.05 9

Selenium .14 .3 .33 .36 .55 9

Sulfur, percent .05 .06 .06 .09 .14 9

Total carbon, percent 1.52 2.15 3.18 3.6 4.79 9

Inorganic carbon, percent .03 .05 .06 .1 .22 9

Organic carbon, percent 1.42 2 3.13 3.47 4.74 9

Thallium .54 .61 .64 .65 .77 9

Antimony 1.1 1.2 1.4 1.7 7 9

Arsenic 12 18 31 58 60 9

Barium 615 685 697 797 875 9

Beryllium 1.6 1.7 1.8 1.8 1.9 9

Bismuth .26 .29 .3 .33 .34 9

Cadmium .24 .29 .36 .4 .58 9

Cerium 42.9 67.4 83.1 86.1 101 9

Chromium 49 96.3 114 118 155 9

Cobalt 18 20.6 23.2 24.7 31.1 9

Copper 27.8 47.6 53.4 64.4 95.2 9

Gallium 16 18 18 19 23 9

Lanthanum 33.9 36.6 43.8 44.1 48.2 9

Lead 19.7 20.6 21.1 22.2 24 9

Lithium 28.9 36.2 36.4 40.5 55.6 9

Manganese 582 787 1,150 2,040 3,080 9

Molybdenum .67 .72 .8 .84 65.4 9

Nickel 11.9 41.6 46.2 52 71.7 9

Niobium 11 17 20 22 26 9

Scandium 8.9 18.5 21 22.1 28.3 9

Silver <2 <2 <2 <2 <2 9

Strontium 149 153 165 201 355 9

Thorium 12.8 14 14.6 16.9 35.4 9

Uranium 2.8 3.2 3.3 3.9 194 9

Vanadium 117 155 158 160 531 9

Yttrium 12.6 21.9 23.3 25 28.6 9

Zinc 83.6 95 105 105 119 9

Aluminum 62,700 71,700 73,800 77,400 87,600 9

Calcium 11,100 12,400 13,000 14,100 16,000 9

Cesium 3.1 3.6 3.6 3.8 7 9

Iron 42,000 53,000 54,000 71,000 120,000 9

Magnesium 8,240 10,600 12,600 13,400 17,100 9

Phosphorus 430 790 860 890 1,100 9

Potassium 16,500 18,600 19,000 20,900 21,700 9

Rubidium 80.3 91.3 98.3 102 123 9

Sodium 7,620 8,270 8,320 10,600 18,100 9

Titanium 5,300 5,400 6,100 6,400 8,600 9

1

Mercury concentration average of split (two) sample analysis from the same composite sample.

Results 27
Table 13. Summary of streambed-sediment-quality guidelines for nine priority-pollutant trace elements in selected streambedsediment samples from the upper Birch Creek watershed near Central, Alaska, 2005.

[NAWQA National median: National median concentrations from NAWQA sampling sites (Gilliom and others, 1998). CB-PEC: Consensus Based Probable 

Effect Concentration (MacDonald and others, 2000). Abbreviations: μg/g, microgram per gram, dry weight; NAWQA, National Water-Quality Assessment; 

NG, no guideline; USGS, U.S. Geological Survey; >, greater than; –, no data]

Constituent

Concentration (μg/g)

Birch Creek sample greater than CB-PEC 

(USGS site identification No.)

Concentration 

greater than 

CB-PEC 

(μg/g)

Birch Creek 

watershed 

median

NAWQA 

National 

median

CB-PEC

Arsenic 31 6.35 33 (15396000) Frying Pan Creek near Miller House, Alaska 52

(652149145074900) North Fork Harrison Creek 0.1 mi above mouth, 

near Central, Alaska

58

(652129145001700) Harrison Creek 0.4 mi above Ptarmigan Gulch, 

near Central, Alaska

60

(652209144573700) Harrison Creek 1.3 mi below Ptarmigan Gulch, 

near Central, Alaska

60

Cadmium .36 .4 4.98 None –

Chromium 114 62 111 (15396000) Frying Pan Creek near Miller House, Alaska 118

(15407200) South Fork Harrison Creek near Central, Alaska 114

(652149145074900) North Fork Harrison Creek 0.1 mi above mouth, 

near Central, Alaska

155

(652209144573700) Harrison Creek 1.3 mi below Ptarmigan Gulch, 

near Central, Alaska

123

(652231144541200) Harrison Creek 0.2 mi above Squaw Creek, near 

Central, Alaska

116

(15407500) Harrison Creek above Bottom Dollar Creek, near Central, 

Alaska

114

Copper 53.4 26 149 None –

Lead 21.1 24.3 128 None –

Mercury 1

.03 .06 1.06 None –

Nickel 46.2 25 48.6 (652149145074900) North Fork Harrison Creek 0.1 mi above mouth, 

near Central, Alaska

71.7

(652209144573700) Harrison Creek 1.3 mi below Ptarmigan Gulch, 

near Central, Alaska

53

(652231144541200) Harrison Creek 0.2 mi above Squaw Creek, near 

Central, Alaska

52

(15407500) Harrison Creek above Bottom Dollar Creek, near Central, 

Alaska

49.1

Selenium .33 .7 NG Sample concentrations do not exceed NAWQA median –

Zinc 105 110 459 None –

1

Mercury concentration average of split (two) sample analysis from the same composite sample.

28  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Comparison of Paired-Site Results 

This section compares water-quality data and traceelement concentrations in streambed sediment for study sites 

located upstream and downstream from placer-mined areas on 

Frying Pan Creek, sites 15395900 and 15396000, and Harrison 

Creek, sites 15407200 and 15407500. Spatial differences for 

field parameters were summarized using a nonparametric 

Wilcoxon rank-sum test. Nonparametric tests do not require 

a normal distribution to detect differences between two 

populations based on random samples from those populations 

(Helsel and Hirsch, 1992). Statistical comparisons were 

reported as significant for tests with calculated p-values less 

than or equal to 0.01. Trace-element data were compiled using 

descriptive statistics and comparative tables. Histograms were 

used to illustrate between-site variations for selected trace 

elements (fig. 10).

Frying Pan Creek

Flow distance from the Upper Frying Pan Creek site 

15395900 to the lower Frying Pan Creek site 15396000 is 

about 1 mi. One unnamed tributary joins Frying Pan Creek 

from the east between the upper and lower sites (fig. 2). 

Bedrock near Frying Pan Creek is primarily quartzite and 

quartzitic schist (Yeend, 1991). Frying Pan Creek has a placermined reach of about 0.25 mi between the upper and lower 

study sites. Placer mining physically altered the natural stream 

channel morphology and removed streamside vegetation. 

Gravel tailings were re-contoured, but only minor vegetation 

has been established on the contoured tailings (fig. 11). The 

placer-mined reach in Frying Pan Creek may contribute 

additional sediment downstream during high-flow events until 

adequate vegetation cover is established.

Figure 11. Reclaimed placer-mined area on Frying Pan Creek near Central, Alaska, June 2004. (Note cutbanks and sparse vegetation 

cover, center of photograph. View is looking downstream toward Frying Pan Creek station 15396000.)

Comparison of Paired-Site Results 29
Water Quality 

There were no statistically significant differences 

(p>0.01) in water-quality field parameters of water 

temperature, pH, specific conductance, or dissolved oxygen 

between the Upper Frying Pan Creek site 15395900 and the 

downstream Frying Pan Creek site 15396000 (table 14). Total 

recoverable-mercury and dissolved-mercury concentrations in 

water were low, less than 0.01 μg/L at both the upstream and 

downstream sample sites (table 10). Mercury concentrations 

were less than the 2.0 μg/L State and Federal maximum 

concentration for safe drinking water.

Major-ion compositions did not vary substantially 

between upstream and downstream sites except for iron and 

manganese (table 15). Iron concentrations were lower at the 

downstream site. Manganese concentrations were an orderof-magnitude higher at the downstream site (15396000) and 

likely reflect ground-water input or increased manganese 

contribution from the unnamed east tributary. Sulfate was the 

Table 14. Statistical comparison of upstream and downstream water-quality field parameters 

at selected sites in Frying Pan Creek and Harrison Creek near Central Alaska, 2004 and 2005, by 

Wilcoxon rank-sum test.

[Abbreviations: μS/cm, microsiemens per centimeter at 25°C, mg/L, milligram per liter; °C, degrees Celsius]

Constituent or property p-value

Significance 

greater than 

99-percent 

confidence

Median

Upstream of 

mined area

Downstream 

of mined area

Frying Pan Creek

15395900 15396000

Water temperature (°C) 0.773 No 7.4 6.9

Specific conductance (μS/cm at 25°C) .500 No 156 197

Dissolved oxygen (mg/L) .562 No 10.9 11.0

pH, field (standard units) .493 No 7.2 7.3

Harrison Creek

15407200 15407500

Water temperature (°C) 0.041 No 9.0 12.7

Specific conductance (μS/cm at 25°C) .000 Yes 96 186

Dissolved oxygen (mg/L) .391 No 10.6 9.7

pH, field (standard units) .000 Yes 7.4 7.8

dominant anion for Frying Pan Creek samples collected during 

2004. Sulfate and bicarbonate concentrations in the Frying Pan 

Creek samples collected during 2005 were about equal, with 

bicarbonate concentrations greater than sulfate concentrations 

(fig. 8; table 15).

Nutrient concentrations were low with no major 

differences between samples from the upstream Frying Pan 

Creek site 15395900 and the downstream Frying Pan Creek 

site 15396000 (table 16). 

One hundred fifteen paired suspended-sediment samples 

were collected in Frying Pan Creek (table A1). The maximum 

suspended-sediment concentration collected using automated 

samplers was 816 mg/L (table 11). The minimum suspendedsediment concentration was less than 1 mg/L. Upstream and 

downstream median suspended-sediment concentrations were 

less than 5 mg/L and were less than the 20 mg/L TMDL set 

by the U.S. Environmental Protection Agency (1996) for the 

upper Birch Creek basin. 

30 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Table 15. Summary of upstream and downstream major-ion concentrations at selected sites in Frying Pan Creek and 

Harrison Creek near Central, Alaska, 2004 and 2005.

[Concentrations are dissolved and in milligrams per liter unless otherwise noted. Abbreviations: mg/L, milligram per liter; <, less than; μg/L, 

microgram per liter; E, estimated]

Constituent or property

2004

concentration

2005

concentration

Upstream Downstream Upstream Downstream

Harrison Creek, August–September Site 15407200 15407500 15407200 15407500

Calcium, dissolved (mg/L as Ca) 19.5 37.2 14.8 30.4

Magnesium, dissolved (mg/L as Mg) 1.94 6.07 1.35 4.95

Potassium, dissolved (mg/L as K) .76 1.24 .74 1.10

Sodium, dissolved (mg/L as Na) .53 .92 .48 .87

Chloride, dissolved (mg/L as Cl) E0.14 .27 .06 .04

Sulfate, dissolved (mg/L as SO4

) 11.8 37.5 11.0 27.0

Fluoride, dissolved (mg/L as F) <.17 <.17 .06 .02

Silica, dissolved (mg/L as SiO2

) 5.96 5.24 4.64 5.48

Iron, dissolved (μg/L as Fe) <6.4 E4.8 3.45 11.6

Manganese, dissolved (μg/L as Mn) <.8 9.80 .80 5.71

Bicarbonate, dissolved (mg/L as HCO3

) 54.2 96.4 46.3 82.8

Acid-neutralizing capacity, alkalinity (mg/L as Ca) 45 80 38 68

Frying Pan Creek, September Site 15395900 15396000 15395900 15396000

Calcium, dissolved (mg/L as Ca) 32.5 34.0 17.9 25.2

Magnesium, dissolved (mg/L as Mg) 15.3 15.7 7.4 11.4

Potassium, dissolved (mg/L as K) 1.84 1.60 1.01 1.16

Sodium, dissolved (mg/L as Na) .61 .65 .34 .43

Chloride, dissolved (mg/L as Cl) .09 .09 .05 .00

Sulfate, dissolved (mg/L as SO4

) 90.3 81.1 48.0 50.8

Fluoride, dissolved (mg/L as F) .03 .03 .05 .04

Silica, dissolved (mg/L as SiO2

) 6.37 6.03 5.03 6.12

Iron, dissolved (μg/L as Fe) 46.8 24.7 53.9 42.9

Manganese, dissolved (μg/L as Mn) 10.2 248 7.3 101

Bicarbonate, dissolved (mg/L as HCO3

) 55.4 69.4 53.9 69.7

Acid-neutralizing capacity, alkalinity (mg/L as Ca) 46 57 42 57

The suspended-sediment concentration samples 

were collected primarily during 2004 and 2005 low-flow 

drought conditions, and thus, were not representative of 

suspended-sediment concentrations that may be associated 

with moderate- to high-flow events. Although there were 

measurable differences in the paired low-flow suspendedsediment samples, they were minor—only a few milligrams 

per liter (tables 11 and A1). Therefore, it is difficult to attach 

much importance to the relatively small downstream increase 

in suspended-sediment concentration in Frying Pan Creek 

during low-flow conditions.

Comparison of Paired-Site Results   31
Trace Elements in Streambed Sediment 

Streambed-sediment trace-element constituents generally 

were comparable for the Frying Pan Creek upstream site 

15395900 and the downstream site 15396000, indicating 

streambed-sediment source material was similar for both sites 

(table 17). However, concentrations of several trace elements 

varied substantially between the upstream and downstream 

sites. Antimony, arsenic, and nickel concentrations were lower 

at the upstream site 15395900. 

Molybdenum and uranium concentrations were higher 

at the upstream site 15395900, than at the downstream site 

15396000. Foster and others (1994), reported the area was 

highly mineralized with scattered occurrences of molybdenum 

and uranium. The variation in molybdenum and uranium 

concentrations, as well as other trace elements, likely was 

related to variations in mineralized bedrock. Mercury and lead 

concentrations did not vary appreciably between the upstream 

and downstream sites. Zinc concentration increased slightly at 

the downstream site (fig. 10; table 17). 

Table 16. Summary of upstream and downstream nutrient concentrations at selected sites in Frying Pan Creek and Harrison 

Creek near Central, Alaska, 2004 and 2005.

[Concentrations are in milligrams per liter unless otherwise noted. Abbreviations: mg/L, milligram per liter; <, less than; E, estimated]

Constituent 

2004

concentration

2005

concentration

Upstream Downstream Upstream Downstream

Harrison Creek, August–September Site 15407200 15407500 15407200 15407500

Phosphorus, total (mg/L as P) <0.004 <0.004 <0.004 <0.004

Phosphorus, dissolved (mg/L as P) <.004 <.004 <.004 E.003

Phosphorus, dissolved orthophosphate (mg/L as P) <.006 <.006 <.006 <.006

Nitrogen, nitrite, dissolved (mg/L as N) <.002 .002 .038 .002

Nitrogen, nitrite plus nitrate, dissolved (mg/L as N) .098 .142 .133 .218

Nitrogen, ammonia, dissolved (mg/L as N) <.010 <.010 <.010 E.005

Nitrogen, ammonia plus organic, dissolved (mg/L as N) <.1 E.08 <.1 .1

Nitrogen, ammonia plus organic, total (mg/L as N) <.1 E.07 E.06 .1

Frying Pan Creek, September Site 15395900 15396000 15395900 15396000

Phosphorus, total (mg/L as P) E0.002 E0.003 <0.004 E0.003

Phosphorus, dissolved (mg/L as P) <.004 E.002 E.003 E.003

Phosphorus, dissolved orthophosphate (mg/L as P) <.006 <.006 <.006 <.006

Nitrogen, nitrite, dissolved (mg/L as N) E.001 E.001 <.002 <.002

Nitrogen, nitrite plus nitrate, dissolved (mg/L as N) .087 .115 .104 .113

Nitrogen, ammonia, dissolved (mg/L as N) E.006 .017 E.006 E.009

Nitrogen, ammonia plus organic, dissolved (mg/L as N) .2 .2 .3 .3

Nitrogen, ammonia plus organic, total (mg/L as N) .2 .2 .3 .2

32 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Table 17. Comparison of upstream and downstream trace-element concentrations in streambed sediment for 

selected sites in Frying Pan Creek near Central, Alaska, 2005.

[Concentrations are in micrograms per gram unless otherwise indicated. Abbreviations: <, less than; –, no data]

Constituent or property

Birch Creek

watershed

median

concentration

Concentration Percent change, 

upstream to 

downstream Upstream site 

15395900

Downstream site 

15396000

Mercury 0.03 0.03 0.04 33

Selenium .33 .14 .24 71

Sulfur, percent .06 .06 .06 0

Total carbon, percent 3.18 2.19 3.18 45

Inorganic carbon, percent .06 .03 .05 67

Organic carbon, percent 3.13 2.16 3.13 45

Thallium .64 .77 .61 -21

Antimony 1.4 1.7 7.0 312

Arsenic 31 18 52 189

Barium 697 809 797 -1

Beryllium 1.8 1.9 1.8 -5

Bismuth .30 .33 .26 -21

Cadmium .36 .29 .36 24

Cerium 83.1 42.9 86.1 101

Chromium 114 49 118 141

Cobalt 23.2 18.0 21.5 19

Copper 53.4 38.9 53.4 37

Gallium 18 23 18 -22

Lanthanum 43.8 36.6 44.1 20

Lead 21.1 19.7 21.1 7

Lithium 36.4 55.6 31.8 -43

Manganese 1,150 582 787 35

Molybdenum .80 65.4 .72 -99

Nickel 46.2 11.9 46.2 288

Niobium 20 11 22 100

Scandium 21 8.9 21 136

Silver <2 <2 <2 –

Strontium 165 355 201 -43

Thorium 14.6 35.4 14.6 -59

Uranium 3.3 194 3.2 -98

Vanadium 158 531 155 -71

Yttrium 23.3 12.6 26.8 113

Zinc 105 83.6 105 26

Aluminum 73,800 87,600 75,700 -14

Calcium 13,000 16,000 14,300 -11

Cesium 3.6 7.0 3.6 -49

Iron 54,000 120,000 53,000 -56

Magnesium 12,600 8,240 12,400 50

Phosphorus 860 430 890 107

Potassium 19,000 18,200 18,700 3

Rubidium 98.3 123 89.4 -27

Sodium 8,320 18,100 10,600 -41

Titanium 6,100 5,500 6,300 15

Minimum -99

Maximum 312

Median 17

Standard Deviation 89

Comparison of Paired-Site Results   33
Harrison Creek

 Flow distance from the upstream site 15407200 on South 

Fork of Harrison Creek to the downstream site 15407500 on 

Harrison Creek above Bottom Dollar Creek is about 15 mi. 

Three tributaries join Harrison Creek from the north in the 

15-mi reach between the upstream and downstream study 

sites. In downstream sequence, the three tributaries are North 

Fork of Harrison Creek, Ptarmigan Gulch, and Squaw Creek 

(fig. 1). From the confluence of the North Fork and South 

Fork, Harrison Creek flows eastward along a gradational 

geologic contact of mafic schist to the north and quartzite and 

quartzitic schist to the south (Yeend, 1991). The North Fork 

of Harrison Creek was mined extensively. Historic mining of 

unknown extent has occurred on Ptarmigan Gulch and Squaw 

Creek. 

There are substantial geomorphic disturbances in the 

stream channel and flood plain from historic placer-mining 

activity along several miles of Harrison Creek (fig. 12). 

Placer mining physically altered the natural stream channel 

morphology and removed streamside vegetation (fig. A4). 

There has been little or no effort to re-contour waste-rock piles 

or remove mining debris. During high flow, the abandoned 

placer-mine areas on Harrison Creek likely will contribute 

large quantities of sediment downstream unless the mined 

areas are reclaimed. The BLM target for starting Harrison 

Creek reclamation work was 2006.

Figure 12. Waste-rock piles and debris from historic placer mining on Harrison Creek near Central Alaska, August 2005. (View is 

looking upstream toward Harrison Creek station 15407200.)

34  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Water Quality 

There are statistically significant differences in median 

specific conductance (p-value = 0.0003) and median pH 

(p-value = 0.0002) between the upstream South Fork Harrison 

Creek site 15407200 and downstream Harrison Creek 

site 15407500 (fig. 6; table 14). There were no significant 

differences in water temperature or dissolved oxygen. 

Median specific conductance for South Fork Harrison Creek, 

site 15407200, was 96 μS/cm, compared to 186 μS/cm 

for Harrison Creek site 15407500. Median pH for South 

Fork Harrison Creek site 15407200 was 7.4 standard units 

compared with Harrison Creek site 15407500 at 7.8 standard 

units.

The downstream increase in specific conductance and pH 

were driven primarily by surface water input from the North 

Fork of Harrison Creek as evidenced by field measurements 

(table 6). On August 18, 2005, at South Fork of Harrison 

Creek site 15407200, the measured discharge was 5.05 ft3

/s, 

specific conductance was 105 μS/cm, and pH was 7.4 standard 

units. In contrast, on the same date at North Fork of Harrison 

Creek site 652149145074900, the measured discharge was 

12.6 ft3/s, more than twice the measured streamflow in the 

South Fork. Specific conductance was 197 μS/cm, nearly 

twice the specific conductance measured in South Fork of 

Harrison Creek, and pH was 7.9, an increase of 0.5 standard 

units. Water-quality field parameters collected in August 2005 

at selected Harrison Creek sites upstream and downstream 

from Ptarmigan Gulch and Squaw Creek show little change 

in specific conductance (171–179 μS/cm) and pH (7.8–7.9) as 

surface water flows through mined areas below the confluence 

of the North Fork and South Fork of Harrison Creek (table 6). 

The moderate range of specific conductance, from about 

90 μS/cm in basin headwater areas of South Fork of Harrison 

Creek, to about 200 μS/cm at sites downstream from the 

North Fork of Harrison Creek, was typical of upland areas in 

the Yukon River basin. Similarly, downstream increases in 

pH from near neutral to more alkaline, likely reflect natural 

changes in hydrogen-ion activity rather than adverse changes 

to more acidic conditions that would be expected if substantial 

acid-mine drainage occurred in placer-mined areas. Bjerklie 

and LaPerriere (1985) detected comparable variations in 

specific conductance and pH for sites sampled in 1982 and 

1983 in the upper Birch Creek watershed and also concluded 

the variations in specific conductance and pH were not a direct 

effect of placer mining.

Except for chloride, fluoride, and silica, majorion concentrations for Harrison Creek were greater for 

the downstream site (15407500) than the upstream site 

(15407200) (table 15). Sulfate-bicarbonate compositions 

did not vary substantially between sites. However, there was 

a substantial increase in manganese concentration at the 

downstream site 15407500. The most common source of both 

iron and manganese in water is naturally occurring chemical 

weathering of iron and manganese-bearing bed material. 

Hence, concentrations of iron and manganese in ground water 

are generally higher than concentrations measured in surface 

waters. Increased manganese concentration at the downstream 

Harrison Creek site 15407500 likely reflects input from 

ground water as well as input from tributaries that drain mafic 

schist bedrock areas.

No major differences were detected in nutrient 

concentrations between the upstream South Fork of Harrison 

Creek and downstream Harrison Creek samples, although 

nitrogen, nitrite plus nitrate concentrations tended to be higher 

at the downstream Harrison Creek site 15407500 (table 16). 

Total-recoverable mercury concentrations and dissolved 

mercury concentrations were low, less than 0.01 μg/L, at the 

upstream South Fork of Harrison Creek sample site 15407200 

and the downstream Harrison Creek sample site 15407500 

(table 10). Mercury concentrations were less than the State 

and Federal maximum concentration for safe drinking water, 

2.0 μg/L.

One hundred and one paired suspended-sediment samples 

were collected using automated samplers at South Fork of 

Harrison Creek site 15407200 and at Harrison Creek site 

15407500 (table A1). The maximum suspended-sediment 

concentration collected using automated samplers was 

290 mg/L (table 11). The minimum suspended-sediment 

concentration was less than 1 mg/L. Median suspendedsediment concentrations were less than 15 mg/L. The median 

suspended-sediment concentrations for the 101 paired samples 

from South Fork of Harrison Creek and Harrison Creek were 

less than the 20 mg/L TMDL set by the USEPA for the upper 

Birch Creek basin in 1996. However, suspended-sediment 

concentration samples were collected primarily during 

2004 and 2005 low-flow drought conditions and thus, were 

not representative of suspended-sediment concentrations 

associated with higher flows. Differences of only a few 

milligrams per liter were measured in the paired low-flow 

suspended-sediment samples (tables 11 and A1). Thus, it is 

difficult to attach much importance to the relatively small 

downstream increase in suspended-sediment concentration in 

Harrison Creek during low-flow conditions. 

Trace Elements in Streambed Sediment 

Except for arsenic and manganese, concentrations of 

selected trace elements in streambed sediment varied by less 

than 36 percent between the upstream and downstream sites, 

indicating no significant change in streambed-sediment source 

between the sample sites (table 18). Manganese concentration 

was considerably higher at the downstream site indicating 

addition of manganese precipitate from ground water or 

changes in streambed-sediment source material. Arsenic 

concentrations were variable in the study area. Mercury, lead, 

and zinc concentrations did not vary appreciably between the 

upstream and downstream sites. 

Comparison of Paired-Site Results   35
Table 18. Comparison of upstream and downstream trace-element concentrations in streambed sediment for 

selected sites in Harrison Creek near Central, Alaska, 2005.

[Concentrations are in micrograms per gram unless otherwise indicated. Abbreviations: <, less than; –, no data]

Constituent or property

Birch Creek

watershed

median

concentration

Concentration Percent change, 

upstream to 

downstream Upstream site 

15407200

Downstream site 

15407500

Mercury 0.03 0.04 0.03 -25

Selenium .33 .55 .36 -35

Sulfur, percent .06 .06 .06 0

Total carbon, percent 3.18 4.79 4.00 -16

Inorganic carbon, percent .06 .05 .06 20

Organic carbon, percent 3.13 4.74 3.94 -17

Thallium .64 .64 .60 -6

Antimony 1.4 1.2 1.1 -8

Arsenic 31 12 23 92

Barium 697 753 638 -15

Beryllium 1.8 1.6 1.7 6

Bismuth .30 .29 .31 7

Cadmium .36 .32 .29 -9

Cerium 83.1 77.6 83.1 7

Chromium 114 114 114 0

Cobalt 23.2 20.6 23.2 13

Copper 53.4 52.3 64.1 23

Gallium 18 18 18 0

Lanthanum 43.8 43.8 42.3 -3

Lead 21.1 20.9 20.6 -1

Lithium 36.4 36.2 36.4 1

Manganese 1,150 742 1,030 39

Molybdenum .8 .8 .7 -13

Nickel 46.2 46.2 49.1 6

Niobium 20 17 21 24

Scandium 21 20.3 21.8 7

Silver <2 <2 <2 --

Strontium 165 149 151 1

Thorium 14.6 13.4 14.4 7

Uranium 3.3 3.3 2.8 -15

Vanadium 158 158 160 1

Yttrium 23.3 24.4 23.3 -5

Zinc 105 105 105 0

Aluminum 73,800 73,000 69,500 -5

Calcium 13,000 11,100 13,000 17

Cesium 3.6 3.7 3.5 -5

Iron 54,000 48,000 54,000 13

Magnesium 12,600 12,600 13,400 6

Phosphorus 860 870 790 -9

Potassium 19,000 19,000 18,600 -2

Rubidium 98.3 96.3 91.3 -5

Sodium 8,320 8,220 8,320 1

Titanium 6,100 5,400 6,900 28

Minimum -35

Maximum 92

Median 0

Standard Deviation 20

36  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Summary and Conclusions

The U.S. Geological Survey, in cooperation with the 

Bureau of Land Management, completed an assessment of 

hydrology, water quality, and trace-element concentrations 

in streambed sediment at one site on upper Birch Creek and 

at paired sites, upstream and downstream from mined areas 

on Frying Pan Creek and Harrison Creek, in anticipation 

of reclamation work scheduled to begin in 2006. Stream 

discharge, water-quality, and trace-element concentration data 

were collected at miscellaneous mined and unmined sites to 

assist in characterizing conditions in the upper Birch Creek 

watershed. Data collection began in September 2001 and 

ended in September 2005.

Primary conclusions and characteristics of streamflow, 

water quality, and trace-element concentrations in streambed 

sediment for sites investigated during the study are 

summarized as follows.

Annual and monthly streamflow in the upper Birch 

Creek watershed were characterized as highly variable 

and precipitation dependent. Flows increased and 

decreased rapidly in response to rainfall and snowmelt 

events because the relatively steep slopes, thin soil 

cover, and permafrost areas in the watershed had a low 

capacity for retaining precipitation. Typically, there 

were two or more periods of relatively sharp discharge 

peaks. The first peak discharges were associated with 

snowmelt runoff. Additional discharge peaks, of similar 

or greater magnitude, occurred after spring snowmelt and 

were related to the location, duration, and intensity of 

precipitation. 

Daily mean peak discharges recorded at the Birch Creek 

stream gage for 2002, 2003, and 2005 were comparable 

at approximately 1,000 ft3

/s. Discharges associated with 

summer precipitation were low in 2004 and 2005 because 

of drought conditions in interior Alaska. Minimum daily 

mean streamflows of 22 ft3/s or less were recorded during 

June, July, August, September, and October.

Water quality was generally good in Birch Creek, 

Harrison Creek, and Frying Pan Creek during the 2004 

and 2005 field seasons. Median water temperatures 

during open-water season were between 7.4 and 

12.7°C. Measured dissolved-oxygen concentrations 

were between 7.3 and 14.7 mg/L. Measured pH was 

near neutral to moderately alkaline ranging from 6.9 to 

7.9 standard units. Specific conductance varied from a 

minimum 52 μS/cm during a June 1, 2005, peak flow on 

Birch Creek to a maximum of 312 μS/cm at Frying Pan 

Creek during late September 2004 low-flow conditions. 

Comparable water-quality field parameter values were 

reported for the upper Birch Creek watershed in the 1980s 

by the Alaska Department of Natural Resources (ADNR). 

Surface waters of the upper Birch Creek watershed were 

1.

2.

calcium-magnesium-bicarbonate waters and are typical 

of Yukon River basin waters. Cation compositions 

were mixed calcium-magnesium, but calcium was the 

predominant cation for all samples. Anion compositions 

for upper Birch Creek and Harrison Creek were primarily 

bicarbonate with minor sulfate; Frying Pan Creek anion 

compositions were mixed sulfate and bicarbonate or 

sulfate with minor bicarbonate. Concentrations of 

nutrients were low at all sample sites. All mercury 

samples collected were at concentrations below the 2.0 

μg/L maximum drinking water mercury contaminant 

level set by Alaska Department of Environmental 

Conservation and the National Primary Drinking Water 

Regulations. Suspended-sediment concentrations were 

low on South Fork of Harrison Creek, Harrison Creek, 

and Frying Pan Creek during 2004 and 2005 and were 

less than the 20 mg/L total maximum daily load set by the 

U.S. Environmental Protection Agency in 1996 for the 

upper Birch Creek basin. Upstream suspended-sediment 

concentrations generally were less than downstream 

suspended-sediment concentrations and concentrations 

typically increased with increased streamflow. The 

maximum suspended-sediment concentration measured 

using automated samplers for Frying Pan Creek was 290 

mg/L and for South Fork of Harrison and Harrison Creek 

was 816 mg/L. 

Trace-element concentrations of mercury, lead, and 

zinc in streambed sediment were less than the National 

Water-Quality Assessment (NAWQA) National median 

concentrations. No mercury, lead, or zinc sample 

concentrations exceeded consensus-based probable 

effect concentrations (CB-PEC). Median concentrations 

of arsenic, chromium, and nickel were greater than the 

NAWQA National median concentrations and several 

sample concentrations exceeded the CB-PEC. Arsenic 

concentrations ranged from 12 to 60 μg/g, chromium 

varied from 49 to 155 μg/g, and nickel fluctuated from 

11.9 to 71.7 μg/g. Elevated arsenic concentrations in 

streambed sediment were expected because previous 

geochemical analyses by the ADNR indicated significant 

concentrations of arsenic in local bedrock. Elevated 

chromium and nickel were likely associated with 

sediment input from weathered mafic-igneous rocks. 

During 2004 and 2005, no substantial changes were 

detected in nutrient, major-ion, or mercury concentrations 

for water samples collected upstream from mined areas 

compared with water samples collected downstream from 

mined areas on Frying Pan Creek and Harrison Creek that 

could not be attributed to natural variation. This was also 

true for dissolved-oxygen concentration, pH, and specific 

conductance—a measure of total dissolved solids. Sample 

sites downstream from mined areas on Harrison Creek 

and Frying Pan Creek had higher median suspendedsediment concentrations, by a few milligrams per liter, 

3.

4.

Summary and Conclusions  37
than respective upstream sites. However, it is difficult to 

attach much importance to the small downstream increase, 

less than 10 mg/L, in median suspended-sediment 

concentration for either basin. No significant miningrelated water or sediment-quality problems were detected 

at study sites investigated in the upper Birch Creek 

watershed during low-flow conditions. 

There are major geomorphic disturbances in the stream 

channel and flood plain along several miles of Harrison 

Creek. Placer mining has physically altered the natural 

stream channel morphology and removed streamside 

vegetation. Little or no effort has been made to re-contour 

waste-rock piles. During high-flow events the abandoned 

placer-mine areas on Harrison Creek will likely contribute 

large quantities of sediment downstream unless the mined 

areas are reclaimed. 

Acknowledgments

The authors thank Ingrid McSweeny, Steve Lundeen, and 

Jon Kostohrys with the Bureau of Land Management Northern 

Field Office for providing their support and efforts in data 

collection activities. 

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40 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Appendix A. Hydrology, Water-Quality, and Trace-Element Data

Figure A1. Stream channel cross-section plots and photographs showing (A) upstream channel and (B) downstream 

channel at South Fork Harrison Creek site 15407200 near Central, Alaska, August 2003. (An arbitrary elevation of 50 feet 

was assigned to a survey hub stake installed at the survey site for reference.)

Left bank Right bank

Water surface July 27, 2003

Right bank Left bank

Water surface, July 27, 2003 

Left bank Right bank

Water surface, July 27, 2003

South Fork Harrison Creek 

Cross section 3

30 feet upstream of crest-stage gage

South Fork Harrison Creek

Cross section 2

at crest-stage gage

South Fork Harrison Creek

Cross section 1

40 feet downstream of crest-stage gage

40

42

44

46

48

50

52

54

40

42

44

46

48

50

52

54

ELEVATION, IN FEET ABOVE ARBITRARY DATUM

Creststage

gage

40

42

44

46

48

50

52

54

0 20 40 60 80 100

DISTANCE, IN FEET

A

Creststage

gage

Creststage

gage

B

Appendix A. Hydrology, Water-Quality, and Trace-Element Data  41
AK19-5003_FigA-2 ELEVATION, IN FEET ABOVE ARBITRARY DATUM

Creststage

gage

DISTANCE, IN FEET

0 20 40 60 80 100 120 140

40

45

50

55

60

40

45

50

55

60

40

45

50

55

60

Harrison Creek

Cross section 3

100 feet upstream

of crest-stage gage

Harrison Creek

Cross section 2

at crest-stage gage

Harrison Creek

Cross section 1

120 feet downstream

of crest-stage gage

Creststage

gage

Creststage

gage

A

B

Right bank Left bank

Water Surface July 27, 2003

Left bank Right bank

Water Surface July 27, 2003

Left bank Right bank

Water Surface July 27, 2003

Figure A2. Stream channel cross-section plots and photographs showing (A) upstream channel and (B) downstream channel 

at Harrison Creek site 15407500 near Central, Alaska, September 2004. (An arbitrary elevation of 50 feet was assigned to a survey 

hub stake installed at the survey site for reference.)

42 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
AK19-5003_FigA-3

A

B

Figure A3. Photographs showing (A) split channel morphology at South Fork of Harrison Creek site 15407200 

and (B) incised channel morphology at Frying Pan Creek site 15396000 near Central, Alaska, September 2005. 

)Views are looking upstream. Crest-stage gage and instrument shelter in right center of photograph B.)

Appendix A. Hydrology, Water-Quality, and Trace-Element Data  43
AK19-5003_FigA-4

A

C

B

D

Figure A4. Photographs showing views of placer-mine tailings in Harrison Creek watershed near Central, Alaska. (A) Oblique 

aerial photograph of Harrison Creek placer-mine tailings, (B) Lower Harrison Creek placer-mine tailings, (C) South Fork Harrison 

Creek placer-mine tailings, and (D) South Fork Harrison Creek placer-mine tailings and stream channel.

44  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Table A1. Summary of daily suspended-sediment concentration for selected sites in Frying Pan Creek and Harrison Creek with 

associated mean daily discharge at Birch Creek stream gage site 15392000 and daily precipitation from nearby climate stations near 

Central, Alaska, 2004 and 2005.

[Abbreviations: USGS Site_ID, U.S. Geological Survey site identification No.; NCDC_ID, Natural Climate Data Center climate station number; Snotel_ID, 

Natural Resources Conservation Service climate station number; in., inch; mg/L, milligram per liter; ft3/s, cubic foot per second; <, less than; E, estimated; –, no 

data]

Date

Suspended sediment concentration (mg/L) Discharge 

(ft3

/s) Precipitation (in.)

Upper Frying 

Pan Creek 

USGS Site_ID 

15395900

Frying Pan 

Creek 

USGS Site_ID 

15396000

South Fork 

Harrison Creek 

USGS Site_ID 

15407200

Harrison Creek 

USGS Site_ID 

15407500

Birch Creek 

USGS Site_ID 

15392000

Birch Creek 

Precipitation 

USGS Site_ID 

15392000

Central 

NCDC_ID 

151466

Eagle 

Summit 

Snotel_ID 

AK45Q05S

Mt Ryan 

Snotel_ID 

AK46Q01S

Monument 

Creek 

Snotel_ID 

AK45Q02S

Circle Hot 

Springs 

NCDC_ID 

501987

2004

08-01-04 – – 2 33 122 0.31 0.20 – 0.5 – 0.13

08-02-04 – – 1 24 140 .00 .02 – .3 – .03

08-03-04 9 14 – – 98 .00 .00 – .0 – .00

08-04-04 13 5 1 26 76 .00 .00 – – – .00

08-05-04 14 6 2 9 65 .00 .00 – .1 – .00

08-06-04 10 5 1 9 57 .02 .00 – – – .00

08-07-04 8 3 1 8 50 .00 .00 – – – .00

08-08-04 3 4 1 4 44 .00 .00 – .1 – .00

08-09-04 – – 1 6 40 .00 .00 – .0 – –

08-10-04 3 2 1 7 38 .00 .00 – – – .00

08-11-04 3 2 1 5 36 .00 .00 – .0 – .00

08-12-04 3 2 1 5 34 .00 .00 – – – .00

08-13-04 4 3 – – 32 .00 .00 – – – .00

08-14-04 2 3 2 7 31 .04 .03 – – – .00

08-15-04 4 2 <1 4 30 .00 .00 – .0 – .00

08-16-04 6 1 1 2 28 .00 .00 – .0 – .00

08-17-04 4 2 1 2 27 .00 .00 – .0 – .00

08-18-04 3 4 <1 5 27 .00 .00 – – – .00

08-19-04 8 2 – – 26 .00 .00 – – – .00

08-20-04 2 2 – – 25 .00 .00 – – – .00

08-21-04 1 2 – – 25 .00 .00 – .0 – .00

08-22-04 1 2 – – 25 .00 .00 – .0 – .00

08-23-04 2 1 – – 25 .00 .00 – – – .00

08-24-04 3 1 – – 25 .00 .00 – – – .00

08-25-04 2 1 – – 24 .00 .00 – .0 – .00

08-26-04 – – – – 24 .00 .00 – – – –

08-27-04 – – – – 23 .00 .00 – .0 – –

08-28-04 – – – – 23 .00 .00 – .0 – –

08-29-04 – – – – 23 .00 .00 – – – –

08-30-04 – – – – 22 .00 .00 – .0 – –

08-31-04 – – 2 7 21 .00 .00 – .0 – –

09-01-04 2 36 4 9 23 .20 .00 – .0 – .00

09-02-04 3 7 4 29 26 .06 .09 – .3 – .01

09-03-04 70 6 3 7 24 .00 .00 – – – .00

09-04-04 5 1 19 8 23 .00 .00 – – – .00

09-05-04 3 1 5 18 23 .00 .04 – .3 – .05

09-06-04 1 3 2 14 22 .00 .00 – .0 – .00

09-07-04 1 3 2 93 21 .00 .00 – – – .00

09-08-04 2 20 2 15 21 .00 .00 – .0 – .00

09-09-04 1 4 2 7 20 .00 .00 – .0 – .00

09-10-04 1 5 158 13 19 .00 .00 – .0 – .00

09-11-04 14 6 12 44 19 .00 .00 – .0 – .00

09-12-04 107 5 2 7 18 .00 .00 – .0 – .00

09-13-04 8 3 1 5 18 .00 .00 – .0 – .00

09-14-04 4 4 2 9 18 .00 .00 – .1 – .00

09-15-04 – – 6 9 16 .00 .00 – – – .00

09-16-04 – – 2 9 15 .00 .01 – – – .00

09-17-04 2 2 3 3 15 .00 .00 – – – .00

09-18-04 1 2 2 6 13 .00 .00 – – – .00

09-19-04 1 1 – – 14 .00 .00 – – – .00

Appendix A. Hydrology, Water-Quality, and Trace-Element Data  45
Date

Suspended sediment concentration (mg/L) Discharge 

(ft3

/s) Precipitation (in.)

Upper Frying 

Pan Creek 

USGS Site_ID 

15395900

Frying Pan 

Creek 

USGS Site_ID 

15396000

South Fork 

Harrison Creek 

USGS Site_ID 

15407200

Harrison Creek 

USGS Site_ID 

15407500

Birch Creek 

USGS Site_ID 

15392000

Birch Creek 

Precipitation 

USGS Site_ID 

15392000

Central 

NCDC_ID 

151466

Eagle 

Summit 

Snotel_ID 

AK45Q05S

Mt Ryan 

Snotel_ID 

AK46Q01S

Monument 

Creek 

Snotel_ID 

AK45Q02S

Circle Hot 

Springs 

NCDC_ID 

501987

2004—Continued

09-20-04 1 <1 – – 15 0.04 0.00 – 0.0 – 0.01

09-21-04 1 1 – – 15 .11 .14 – .2 – .19

09-22-04 1 2 – – 15 .17 .04 – .0 – .03

09-23-04 1 1 – – 15 .23 .00 – .0 – .00

09-24-04 3 2 – – 15 .00 .38 – .3 – .21

09-25-04 – – – – 14 .03 – – .1 – .00

09-26-04 – – – – 14 .35 .19 – .1 – .21

09-27-04 – – – – 15 .00 .01 – .1 – .00

09-28-04 – – – – 15 .00 .00 – .0 – .00

09-29-04 – – – – 15 .00 .00 – .0 – .00

09-30-04 – – – – 15 .02 .00 – .1 – .00

2005

06-01-05 – – – – 1030 0.31 0.48 0.60 0.6 1.00 1.20

06-02-05 – – – – 609 .11 .23 .20 .0 .10 .27

06-03-05 – – – – 380 .07 .02 .10 .0 .30 .09

06-04-05 – – – – 249 .00 .01 .00 .0 .00 .08

06-05-05 – – – – 184 .00 .00 .00 .0 .00 –

06-06-05 – – – – 140 .00 .00 .00 .0 .00 –

06-07-05 – – – – 112 .00 .00 .00 .1 .00 .00

06-08-05 – – – – 93 .00 .00 .00 .0 .00 .00

06-09-05 – – – – 80 .00 .00 .00 .0 .00 .00

06-10-05 – – – – 71 .00 .00 .00 .0 .00 .00

06-11-05 – – – – 66 .42 .00 .20 .4 .00 .00

06-12-05 – – – – 93 .07 .00 .00 .2 .10 .19

06-13-05 – – – – 137 .00 .10 .50 .0 .00 .01

06-14-05 – – – – 100 .00 .00 .00 .0 .00 –

06-15-05 – – – – 80 .00 .00 .00 .1 .00 .00

06-16-05 – – – – 73 .98 .00 .00 .3 2.50 .00

06-17-05 – – – – 71 .00 .02 .00 .0 .00 .00

06-18-05 – – – – 61 .00 .00 .10 .0 .00 –

06-19-05 – – – – 56 .13 .00 .00 .3 1.20 .00

06-20-05 – – – – 54 .01 .00 .10 .0 .30 .00

06-21-05 – – – – 49 .00 .00 .00 .0 .00 .00

06-22-05 – – – – 45 .00 .00 .00 .1 .20 .00

06-23-05 – – – – 41 .00 .03 .00 .0 .00 .03

06-24-05 – – – – 37 .00 .00 .00 .1 .20 –

06-25-05 4 3 – – 35 .01 .00 .00 .0 .00 –

06-26-05 5 2 – – 32 .00 .00 .00 .0 .00 –

06-27-05 5 2 – – 29 .00 .00 .00 .0 .10 .00

06-28-05 4 21 2 1 27 – .00 .00 .0 .00 .00

06-29-05 2 2 2 2 40 – .00 .00 .0 .00 .00

06-30-05 3 2 1 3 130 – .00 .30 .1 .00 .00

07-01-05 11 56 1 31 574 – .37 1.10 2.0 1.10 .38

07-02-05 5 39 1 79 350 – .36 .00 .1 .10 .30

07-03-05 3 20 1 18 250 – .18 .20 .0 .30 .50

07-04-05 3 6 3 105 200 – .11 .40 .2 .20 .02

07-05-05 2 5 1 16 165 .00 .21 .00 .0 .10 .20

07-06-05 2 3 – – 126 .00 .15 .00 .1 .00 –

07-07-05 5 26 3 290 194 .42 .38 .50 .4 1.20 .92

Table A1. Summary of daily suspended-sediment concentration for selected sites in Frying Pan Creek and Harrison Creek with 

associated mean daily discharge at Birch Creek stream gage site 15392000 and daily precipitation from nearby climate stations near 

Central, Alaska, 2004 and 2005.—Continued

[Abbreviations: USGS Site_ID, U.S. Geological Survey site identification No.; NCDC_ID, Natural Climate Data Center climate station number; Snotel_ID, 

Natural Resources Conservation Service climate station number; in., inch; mg/L, milligram per liter; ft3/s, cubic foot per second; <, less than; E, estimated; –, no 

data]

46  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Date

Suspended sediment concentration (mg/L) Discharge 

(ft3

/s) Precipitation (in.)

Upper Frying 

Pan Creek 

USGS Site_ID 

15395900

Frying Pan 

Creek 

USGS Site_ID 

15396000

South Fork 

Harrison Creek 

USGS Site_ID 

15407200

Harrison Creek 

USGS Site_ID 

15407500

Birch Creek 

USGS Site_ID 

15392000

Birch Creek 

Precipitation 

USGS Site_ID 

15392000

Central 

NCDC_ID 

151466

Eagle 

Summit 

Snotel_ID 

AK45Q05S

Mt Ryan 

Snotel_ID 

AK46Q01S

Monument 

Creek 

Snotel_ID 

AK45Q02S

Circle Hot 

Springs 

NCDC_ID 

501987

2005—Continued

07-08-05 3 28 2 44 255 0.04 0.21 0.00 0.1 0.10 0.24

07-09-05 3 6 1 25 178 .27 .00 .80 .2 .10 –

07-10-05 13 74 2 58 290 .14 .14 .40 .3 .60 .00

07-11-05 6 25 2 269 .15 .00 .10 .2 .20 .02

07-12-05 4 10 2 13 225 .04 .00 .10 .1 .00 .00

07-13-05 4 6 3 12 183 .00 .07 .10 .0 .00 .10

07-14-05 3 4 1 14 152 .00 .00 .00 .0 .00 .00

07-15-05 6 5 1 11 122 .00 .00 .00 .0 .00 .00

07-16-05 4 12 5 19 118 .05 .00 .10 .1 .20 .00

07-17-05 3 7 2 26 170 .38 .79 .10 .6 .80 .31

07-18-05 91 816 2 57 300 .06 .66 .30 .7 .30 .75

07-19-05 3 23 2 76 230 .00 .02 .00 .0 .00 .00

07-20-05 8 45 <1 6 175 .00 .00 .00 .0 .10 .00

07-21-05 7 18 <1 28 146 .00 .00 .10 .0 .10 .00

07-22-05 3 13 <1 22 126 .00 .00 .00 .0 .00 .00

07-23-05 3 6 <1 10 109 .00 .00 .00 .0 .00 –

07-24-05 3 6 <1 11 95 .00 .00 .00 .0 .20 –

07-25-05 3 5 <1 8 85 .00 .00 .00 .0 .00 .00

07-26-05 2 6 3 9 76 .00 .00 .00 .0 .00 .00

07-27-05 3 4 <1 9 69 .00 .00 .00 .0 .10 .00

07-28-05 2 3 2 5 63 .00 .00 .00 .0 .10 .00

07-29-05 1 4 1 7 60 .06 .00 .10 .1 .10 –

07-30-05 2 2 3 6 59 .07 .10 .00 .1 .10 –

07-31-05 3 1 1 6 56 .00 .00 .20 .0 .10 .13

08-01-05 2 1 2 6 54 .00 .00 .10 .0 .10 .00

08-02-05 1 4 <1 8 53 .02 .58 .00 .0 .00 .53

08-03-05 1 2 1 5 50 .00 .11 .20 .0 .00 .13

08-04-05 1 3 2 6 48 .13 .00 .00 .1 .10 .00

08-05-05 2 2 1 4 50 .02 .00 .10 .1 .10 –

08-06-05 2 2 2 5 51 .08 .06 .10 .2 .60 –

08-07-05 2 2 1 3 49 .00 .01 .10 .0 .00 .04

08-08-05 2 4 1 5 47 .00 .00 .00 .0 .00 –

08-09-05 2 2 1 3 46 .00 .00 .00 .0 .00 –

08-10-05 2 2 1 11 44 .00 .00 .00 .0 .00 –

08-11-05 2 1 1 3 43 .00 .00 .00 .0 .00 –

08-12-05 1 2 1 1 42 .00 .00 .00 .0 .30 –

08-13-05 13 1 – – 41 .00 .00 .00 .2 .00 –

08-14-05 1 5 2 2 40 .00 .00 .00 .0 .00 –

08-15-05 2 1 1 2 40 .00 .00 .00 .0 .00 –

08-16-05 1 2 1 3 39 .00 .00 .00 .0 .10 .00

08-17-05 1 2 2 2 40 .00 .00 – .1 .10 .00

08-18-05 1 3 1 2 39 .00 .00 – .0 .00 .00

08-19-05 1 5 1 3 39 .00 .00 – 5.7 .00 .00

08-20-05 1 1 2 2 39 .00 .00 .10 .0 .10 –

08-21-05 1 2 1 2 39 .01 .00 .10 .1 .10 –

08-22-05 1 1 1 2 38 .00 .02 .00 .0 .00 .00

08-23-05 1 2 1 2 38 .00 .00 .00 .0 .10 .00

08-24-05 2 2 1 3 41 .13 .00 .00 – .00 .00

08-25-05 2 2 <1 3 44 .04 .14 .20 – .30 .06

Table A1. Summary of daily suspended-sediment concentration for selected sites in Frying Pan Creek and Harrison Creek with 

associated mean daily discharge at Birch Creek stream gage site 15392000 and daily precipitation from nearby climate stations near 

Central, Alaska, 2004 and 2005.—Continued

[Abbreviations: USGS Site_ID, U.S. Geological Survey site identification No.; NCDC_ID, Natural Climate Data Center climate station number; Snotel_ID, 

Natural Resources Conservation Service climate station number; in., inch; mg/L, milligram per liter; ft3/s, cubic foot per second; <, less than; E, estimated; –, no 

data]

Appendix A. Hydrology, Water-Quality, and Trace-Element Data  47
Date

Suspended sediment concentration (mg/L) Discharge 

(ft3

/s) Precipitation (in.)

Upper Frying 

Pan Creek 

USGS Site_ID 

15395900

Frying Pan 

Creek 

USGS Site_ID 

15396000

South Fork 

Harrison Creek 

USGS Site_ID 

15407200

Harrison Creek 

USGS Site_ID 

15407500

Birch Creek 

USGS Site_ID 

15392000

Birch Creek 

Precipitation 

USGS Site_ID 

15392000

Central 

NCDC_ID 

151466

Eagle 

Summit 

Snotel_ID 

AK45Q05S

Mt Ryan 

Snotel_ID 

AK46Q01S

Monument 

Creek 

Snotel_ID 

AK45Q02S

Circle Hot 

Springs 

NCDC_ID 

501987

2005—Continued

08-26-05 2 5 1 19 43 0.00 0.11 – – 0.10 0.15

08-27-05 2 1 1 5 44 .04 .01 .10 – .00 .05

08-28-05 1 1 1 4 46 .00 .05 .00 1.0E .00 .00

08-29-05 3 1 1 4 47 .00 .00 .00 .0 .00 .00

08-30-05 1 25 <1 4 46 .03 .00 – .0 .00 –

08-31-05 1 3 1 6 49 .10 .00 .10 – .00 .05

09-01-05 1 2 <1 5 51 .01 .10 .00 .5E .00 –

09-02-05 1 2 1 6 51 .00 .00 .10 .0 .00 –

09-03-05 1 22 <1 5 50 .01 .02 – .0 .00 –

09-04-05 – – <1 6 49 .01 .02 – .0 .00 –

09-05-05 – – – – 48 .00 .07 .10 .0 .00 –

09-06-05 – – – – 48 .02 .00 .00 .0 .00 –

09-07-05 – – – – 50 .07 .19 .10 – .00 –

09-08-05 – – – – 54 .00 .10 .20 .4 .00 –

09-09-05 – – – – 56 .02 .00 .00 .0 .00 –

09-10-05 – – – – 58 .00 .00 .10 .2 .00 –

09-11-05 – – – – 58 .00 .00 .00 .0 .00 –

09-12-05 – – – – 59 .13 .00 .00 .0 – –

09-13-05 – – – – 67 .02 .17 .10 .1 .10 –

09-14-05 – – – – 72 .02 .04 .10 – .10 –

09-15-05 – – – – 73 .00 .05 .00 .1 – –

09-16-05 – – – – 72 .00 .00 .00 .0 – –

09-17-05 – – – – 69 .00 .00 .00 .0 .10 –

09-18-05 – – – – 67 .01 .05 – – – –

09-19-05 – – – – 63 .00 .16 – .2E – –

09-20-05 – – – – 61 .01 .02 – – – –

09-21-05 – – – – 62 .01 .06 .40 – .30 –

09-22-05 – – – – 71 .06 .05 .10 .2 .10 –

09-23-05 – – – – 96 .20 .07 .20 – .40 –

09-24-05 – – – – 210 .36 .17 .20 .5 .00 –

09-25-05 – – – – 281 .03 .11 .50 .5 1.00 –

09-26-05 – – – – 268 .01 .05 .10 – .30 –

09-27-05 – – – – 236 .00 .06 .10 – – –

09-28-05 – – – – 197 .00 .14 .00 – .40 –

09-29-05 – – – – 160 .00 .41 .10 1.0E .00 –

09-30-05 – – – – 137 .04 .07 .00 .1 .10 –

Table A1. Summary of daily suspended-sediment concentration for selected sites in Frying Pan Creek and Harrison Creek with 

associated mean daily discharge at Birch Creek stream-gage site 15392000 and daily precipitation from nearby climate stations near 

Central, Alaska, 2004 and 2005.—Continued

[Abbreviations: USGS Site_ID, U.S. Geological Survey site identification No.; NCDC_ID, Natural Climate Data Center climate station number; Snotel_ID, 

Natural Resources Conservation Service climate station number; in., inch; mg/L, milligram per liter; ft3/s, cubic foot per second; <, less than; E, estimated; –, no 

data]

48  Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Table A2. Summary of trace-element concentrations in streambed-sediment samples for selected sites in the upper Birch Creek 

watershed near Central, Alaska, 2005.

[Concentrations are in micrograms per gram unless otherwise indicated. Bold values indicate maximum. Abbreviations: <, less than; –, no data]

Constituent

NWIS 

parameter 

code

Sample 

reporting 

level

Site name (site identification No.)

Birch Creek above 

Twelvemile Creek 

near Miller House 

(15392000)

Upper Frying Pan 

Creek near Miller 

House 

(15395900)

Frying Pan Creek 

near Miller House 

(15396000)

South Fork Harrison 

Creek near Central 

(15407200)

North Fork Harrison 

Creek 0.1 mile above 

mouth near Central 

(652149145074900)

Mercury 34910 0.02 0.05 0.03 0.04 0.04 0.03

Selenium 34950 .1 .3 .14 .24 .55 .33

Sulfur, percent 34970 .05 .06 .06 .06 .06 .05

Total carbon, percent 49267 .01 1.52 2.19 3.18 4.79 1.66

Inorganic carbon, percent 49269 .01 .1 .03 .05 .05 .03

Organic carbon, percent 49266 .01 1.42 2.16 3.13 4.74 1.63

Thallium 4064 .08 .67 .77 .61 .64 .62

Antimony 34795 .04 2 1.7 7 1.2 1.7

Arsenic 34800 1 14 18 52 12 58

Barium 34805 .2 875 809 797 753 615

Beryllium 34810 .03 1.8 1.9 1.8 1.6 1.9

Bismuth 34816 .06 .28 .33 .26 .29 .33

Cadmium 34825 .007 .24 .29 .36 .32 .58

Cerium 34835 .1 91.9 42.9 86.1 77.6 101

Chromium 34840 .5 96.3 49 118 114 155

Cobalt 34845 .03 18.4 18 21.5 2.6 31.1

Copper 34850 2 27.8 38.9 53.4 52.3 95.2

Gallium 34860 .02 18 23 18 18 21

Lanthanum 34885 .05 46 36.6 44.1 43.8 48.2

Lead 34890 .4 22.2 19.7 21.1 2.9 24

Lithium 34895 .3 42.9 55.6 31.8 36.2 4.5

Manganese 34905 .7 2,040 582 787 742 1,150

Molybdenum 34915 .05 .67 65.4 .72 .8 .99

Nickel 34925 .3 34.6 11.9 46.2 46.2 71.7

Niobium 34930 .1 22 11 22 17 26

Scandium 34945 .04 16.7 8.9 21 2.3 28.3

Silver 34955 2 <2 <2 <2 <2 <2

Strontium 34965 .8 222 355 201 149 153

Thorium 34980 .1 17.2 35.4 14.6 13.4 16.9

Uranium 35000 .02 4.2 194 3.2 3.3 3.7

Vanadium 35005 .2 117 531 155 158 206

Yttrium 35010 .05 2.8 12.6 26.8 24.4 28.6

Zinc 35020 3 95 83.6 105 105 119

Aluminum 65170 50 77,400 87,600 75,700 73,000 79,500

Calcium 65171 100 11,400 16,000 14,300 11,100 14,100

Cesium 65172 .003 4 7 3.6 3.7 3.6

Iron 65173 50 42,000 120,000 53,000 48,000 68,000

Magnesium 65174 6 10,400 8,240 12,400 12,600 17,100

Phosphorus 65175 5 680 430 890 870 1,100

Potassium 65176 20 20,900 18,200 18,700 19,000 21,100

Rubidium 65177 .01 102 123 89.4 96.3 102

Sodium 65178 20 11,000 18,100 10,600 8,220 7,620

Titanium 65179 40 5,300 5,500 6,300 5,400 8,600

Appendix A. Hydrology, Water-Quality, and Trace-Element Data  49
Site name (site identification No.)

Minimum Maximum Median

Constituent

Harrison Creek 0.4

mile above Ptarmigan 

Gulch near Central 

(652129145001700)

Harrison Creek 1.3

miles below Ptarmigan 

Gulch near Central 

(652209144573700)

Harrison Creek 0.2 

mile above Squaw 

Creek near Central 

(652231144541200)

Harrison Creek 

above Bottom Dollar 

Creek near Central 

(15407500)

Mercury 0.04 0.03 0.03 0.03 0.03 0.05 0.03

Selenium .36 .33 .38 .36 .14 .55 .33

Sulfur, percent .13 .14 .09 .06 .05 .14 .06

Total carbon, percent 3.6 2.15 3.53 4 1.52 4.79 3.18

Inorganic carbon, percent .22 .15 .06 .06 .03 .22 .06

Organic carbon, percent 3.38 2 3.47 3.94 1.42 4.74 3.13

Thallium .54 .65 .64 .6 .54 .77 .64

Antimony 1.1 1.4 1.3 1.1 1.1 7 1.4

Arsenic 60 60 31 23 12 60 31

Barium 685 697 690 638 615 875 697

Beryllium 1.6 1.8 1.8 1.7 1.6 1.9 1.8

Bismuth .29 .3 .34 .31 .26 .34 .3

Cadmium .37 .4 .46 .29 .24 .58 .36

Cerium 67 67.4 85.7 83.1 42.9 101 83.1

Chromium 93.3 123 116 114 49 155 114

Cobalt 23.8 26 24.7 23.2 18 31.1 23.2

Copper 47.6 64.4 64.9 64.1 27.8 95.2 53.4

Gallium 16 19 18 18 16 23 18

Lanthanum 35.4 33.9 43.8 42.3 33.9 48.2 43.8

Lead 2.2 22 23.3 2.6 19.7 24 21.1

Lithium 28.9 37 36.4 36.4 28.9 55.6 36.4

Manganese 3,080 2,150 1,290 1,030 582 3,080 1,150

Molybdenum .79 .84 .82 .7 .67 65.4 .8

Nickel 41.6 53 52 49.1 11.9 71.7 46.2

Niobium 17 19 20 21 11 26 20

Scandium 18.5 22.1 22.3 21.8 8.9 28.3 21

Silver <2 <2 <2 <2 <2 <2 <2

Strontium 173 165 160 151 149 355 165

Thorium 12.8 14 15.8 14.4 12.8 35.4 14.6

Uranium 3 3.9 3.2 2.8 2.8 194 3.3

Vanadium 130 159 156 160 117 531 158

Yttrium 22.5 21.9 25 23.3 12.6 28.6 23.3

Zinc 89.8 104 115 105 83.6 119 105

Aluminum 62,700 73,800 71,700 69,500 62,700 87,600 73,800

Calcium 13,600 12,400 12,600 13,000 11,100 16,000 13,000

Cesium 3.1 3.6 3.8 3.5 3.1 7 3.6

Iron 71,000 78,000 54,000 54,000 42,000 120,000 54,000

Magnesium 10,600 14,300 12,600 13,400 8,240 17,100 12,600

Phosphorus 860 830 920 790 430 1,100 860

Potassium 16,500 21,700 19,900 18,600 16,500 21,700 19,000

Rubidium 8.3 102 98.3 91.3 8.3 123 98.3

Sodium 8,830 8,270 8,270 8,320 7,620 18,100 8,320

Titanium 5,400 6,100 6,400 6,900 5,300 8,600 6,100

Table A2. Summary of trace-element concentrations in streambed-sediment samples for selected sites in the upper Birch Creek 

watershed near Central, Alaska, 2005.—Continued

[Concentrations are in micrograms per gram unless otherwise indicated. Abbreviations: <, less than; –, no data]

50 Hydrology, Water Quality, and Trace Elements, Birch Creek Watershed, Central Alaska, 2001–05
Manuscript approved for publication, June 26, 2007

Prepared by the USGS Publishing Network, 

Debra Grillo

Jacqueline Olson

Bobbie Jo Richey

Cheri Yoesting

For more information concerning the research in this report, contact the 

Alaska Science Center

U.S. Geological Survey

4230 University Drive, Suite 201

Anchorage, Alaska 99508-4664

http://alaska.usgs.gov
SIR 2007–5124 Kennedy and Langley Assessment of Hydrology, Water Quality, and Trace Elements in Selected Placer-Mined Creeks in the Birch Creek Watershed near Central, Alaska, 2001–05