Water-Quality Conditions of Chester Creek,

Anchorage, Alaska, 1998 2001

Prepared as part of the

National Water-Quality Assessment Program

Scientific Investigations Report 2006-5229

U.S. Department of the Interior

U.S. Geological Survey
Cover Photograph. Chester Creek at Arctic Boulevard looking upstream (east), May 21, 2003. Photograph taken by Janet P. Curran, 

U.S. Geological Survey.
Water-Quality Conditions of

Chester Creek, Anchorage,

Alaska, 1998–2001

By Roy L. Glass and Robert T. Ourso

Prepared as part of the National Water-Quality Assessment Program

Scientific Investigations Report 2006–5229

U.S. Department of the Interior

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

DiRk kemPThORNe, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

For Additional Information:

U.S. Geological Survey, Alaska Science Center, Chief Water Resources Office, 4230 University Dr., Suite 201, Anchorage, AK 99508-4664.

Information regarding the National Water-Quality Assessment (NAWQA) Program is available on the Internet via the 

World Wide Web: http://water.usgs.gov/nawqa/

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

natural hazards, and the environment:

World Wide Web: http://www.usgs.gov

Telephone: 1–888–ASK–USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. 

Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Glass, Roy L., and Ourso, Robert T., 2006, Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998–2001; 

U.S. Geological Survey, Scientific Investigations Report 2006-5229.
iii

Forword

The U.S. Geological Survey (USGS) is committed to serve the Nation with accurate and timely 

scientific information that helps enhance and protect the overall quality of life, and facilitates 

effective management of water, biological, energy, and mineral resources. Information on 

the quality of the Nation’s water resources is of critical interest to the USGS because it is so 

integrally linked to the long-term availability of water that is clean and safe for drinking and 

recreation and that is suitable for industry, irrigation, and habitat for fish and wildlife. Escalating 

population growth and increasing demands for the multiple water uses make water availability, 

now measured in terms of quantity and quality, even more critical to the long-term sustainability 

of our communities and ecosystems. 

The USGS implemented the National Water-Quality Assessment (NAWQA) Program to support 

national, regional, and local information needs and decisions related to water-quality management and policy. Shaped by and coordinated with ongoing efforts of other Federal, State, 

and local agencies, the NAWQA Program is designed to answer: What is the condition of our 

Nation’s streams and ground water? How are the conditions changing over time? How do natural features and human activities affect the quality of streams and ground water, and where are 

those effects most pronounced? By combining information on water chemistry, physical characteristics, stream habitat, and aquatic life, the NAWQA Program aims to provide science-based 

insights for current and emerging water issues. NAWQA results can contribute to informed 

decisions that result in practical and effective water-resource management and strategies that 

protect and restore water quality. 

Since 1991, the NAWQA Program has implemented interdisciplinary assessments in more 

than 50 of the Nation’s most important river basins and aquifers, referred to as Study Units. 

Collectively, these Study Units account for more than 60 percent of the overall water use and 

population served by public water supply and are representative of the Nation’s major hydrologic landscapes, priority ecological resources, and agricultural, urban, and natural sources of 

contamination. 

Each assessment is guided by a nationally consistent study design and methods of sampling 

and analysis. The assessments thereby build local knowledge about water-quality issues and 

trends in a particular stream or aquifer while providing an understanding of how and why water 

quality varies regionally and nationally. The consistent, multi-scale approach helps to determine 

if certain types of water-quality issues are isolated or pervasive and allows direct comparisons 

of how human activities and natural processes affect water quality and ecological health in the 

Nation’s diverse geographic and environmental settings. Comprehensive assessments on pesticides, nutrients, volatile organic compounds, trace metals, and aquatic ecology are developed at 

the national scale through comparative analysis of the Study-Unit findings. 

The USGS places high value on the communication and dissemination of credible, timely, and 

relevant science so that the most recent and available knowledge about water resources can be 

applied in management and policy decisions. We hope this NAWQA publication will provide you 

the needed insights and information to meet your needs and thereby, foster increased awareness and involvement in the protection and restoration of our Nation’s waters. 
iv

The NAWQA Program recognizes that a national assessment by a single program cannot 

address all water-resource issues of interest. External coordination at all levels is critical for a 

fully integrated understanding of watersheds and for cost-effective management, regulation, 

and conservation of our Nation’s water resources. The Program, therefore, depends extensively on the advice, cooperation, and information from other Federal, State, interstate, Tribal, 

and local agencies, non-government organizations, industry, academia, and other stakeholder 

groups. The assistance and suggestions of all are greatly appreciated. 

Robert M. Hirsch

Associate Director for Water
v

Contents

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

introduction.....................................................................................................................................................2

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

Data Collection and Analysis .......................................................................................................................5

Water......................................................................................................................................................5

Sediment ................................................................................................................................................6

Fish Tissue .............................................................................................................................................7

Aquatic Communities ..........................................................................................................................7

Water-Quality Characteristics .....................................................................................................................7

Streamflow ............................................................................................................................................7

Field measurements ............................................................................................................................7

inorganic Constituents ........................................................................................................................8

Fecal-indicator Bacteria ...................................................................................................................13

Organic Constituents .........................................................................................................................15

Pesticides ....................................................................................................................................15

Volatile Organic Compounds ....................................................................................................15

Semivolatile Organic Compounds ...........................................................................................15

Chemical Analyses of Streambed and Lakebed Sediments .................................................................18

Trace elements ...................................................................................................................................18

Semivolatile Organic Compounds ...................................................................................................20

Organochlorine Pesticides and Polychlorinated Biphenyls .......................................................22

Chemical Analyses of Fish Tissues ...........................................................................................................22

Trace elements ...................................................................................................................................22

Organochlorine Pesticides and Polychlorinated Biphenyls .......................................................22

ecological Characteristics .........................................................................................................................22

Physical environment ........................................................................................................................22

Algae ....................................................................................................................................................25

Benthic macroinvertebrates ............................................................................................................25

Fish .......................................................................................................................................................25

Summary and Conclusions .........................................................................................................................26

References Cited..........................................................................................................................................29

Figures

1. major streams in the metropolitan area of Anchorage, Alaska ...............................................3

2. Land cover in the Chester Creek watershed during 2000 ..........................................................4

3. Sampling sites in the Chester Creek watershed, 1998-2001 .....................................................4

4. Discharge hydrograph for Chester Creek from gage at Arctic Blvd. showing 

 time distribution and flow distribution of water samples ........................................................8

5. Daily mean water temperature for Chester Creek at Arctic Boulevard, water 

 years 1999 to 2001.........................................................................................................................12
vi

6. Specific conductance and daily discharge for Chester Creek at Arctic Boulevard, 

 water year 2001............................................................................................................................13

7. Trilinear diagram showing the major-ion compositions of 49 water samples

 collected from Chester Creek at Arctic Boulevard, water years 1999-2001 ......................14

8. Total nitrogen (ammonia plus organic nitrogen) and total phosphorus in water 

 from Chester Creek at Arctic Boulevard, water years 1999-2001 ........................................14

9. Temporal trends in lead concentrations in streambed sediments and cores 

 of lakebed sediments from the Chester Creek watershed, 1970-2000 ................................21

10. Temporal trends in zinc concentrations in streambed sediments and cores 

 of lakebed sediments from the Chester Creek watershed, 1970-2000 ................................21

11. Temporal trends in total DDT concentrations in sediment cores from 

 Westchester Lagoon and hillstrand Pond, 1970-2000 ............................................................23

12. Temporal trends in total PCB concentrations in sediment cores from 

 Westchester Lagoon and hillstrand Pond, 1970-2000 ............................................................23

13. Reaches associated with the water-sampling sites: (a) South Branch of 

 South Fork Chester Creek at Tank Trail, (b) South Branch of South Fork Chester 

 Creek at Boniface Parkway, and (c) Chester Creek at Arctic Boulevard ..........................26

14. Relation of the proportion of algae that prefer water enriched with dissolved 

 minerals (halophilic algae) to specific conductance .............................................................28

15. Dominant macroinvertebrate groups ..........................................................................................28

Tables

1. Sampling sites in the Chester Creek watershed, 1998-2001 .....................................................5

2. Statistical summary of selected water-quality data from Chester Creek, 1998-2001 ...........9

3. Summary of organic compounds detected in water sampled from Chester Creek 

 at Arctic Boulevard, 1998-2001...................................................................................................16

4. Concentrations of selected trace elements and organic compounds in streambed 

 and lakebed sediments from the Chester Creek watershed, 1998-2001 .............................19

5. Concentrations of selected trace elements and organic compounds in whole 

 slimy sculpin collected from Chester Creek at Arctic Boulevard and other streams 

 and rivers in the Cook inlet Basin, 1998-2001 ..........................................................................24

6. Physical characteristics for three reaches along Chester Creek ..........................................27

7. Abundance of fish in three reaches of Chester Creek .............................................................29
vii

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

Multiply By To obtain

Length

inch (in.) 	 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 	 4,047 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2)

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

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

°F=(1.8×°C)+32

ABBREVIATED WATER-QUALITY UNITS

Chemical concentration and water temperature are given only in metric units. Specific conductance is given in 

microsiemens per centimeter (μS/cm) at 25°C. Chemical concentration in water is given in milligrams per liter (mg/L) 

or micrograms per liter (mg/L). Concentrations of coliform bacteria are expressed as the number of colonies per 100 

milliliter (col/100 mL) of sample. Concentrations of trace elements in sediment are given in micrograms per gram, dry 

weight (μg/g), whereas concentrations of organic compounds in sediment are given in micrograms per kilogram, dry 

weight (μg/kg). Similarly, chemical concentration in fish tissue is given in micrograms per gram wet weight (μg/g) or 

micrograms per kilogram wet weight (μg/kg).

WATER YEAR

Water year is the 12-month period, October 1 through September 30. The water year is designated by the calendar year 

in which it ends and includes 9 of the 12 months. Thus, the water year ending September 30, 1999, is called the “1999 

water year.”

MAP NUMBERING SYSTEM

The map numbers in this report follow the map numbering system for stream-gaging stations and water-qualitymonitoring sites in previous Cook Inlet Basin National Water-Quality Assessment reports.

Acronyms used in this report:

cm centimeters

DDT dichloro-diphenyl-trichloroethane

DO dissolved oxygen

EPT Ephemeroptera, Plecoptera, and Trichoptera

HAL Lifetime Health Advisory

MCL Maximum Contaminant Level

mi2 miles squared

MTBE Methyl tert-butyl ether

NAWQA National Water-Quality Assessment Program

NWQL National Water-Quality Laboratory

PAH polycyclic aromatic hydrocarbon

PCB polychlorinated biphenyls

PEL Probable Effect Level

SPMD semipermeable membrane sampling 

devices

SVOC semivolatile organic compounds

USEPA United States Environmental 

Protection Agency

USGS United States Geological Survey

VOC volatile organic compounds
viii

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Water-Quality Conditions of Chester Creek

Anchorage, Alaska, 1998–2001

Abstract

Between October 1998 and September 2001, the 

U.S. Geological Survey’s National Water-Quality Assessment Program evaluated the water-quality conditions of 

Chester Creek, a stream draining forest and urban settings 

in Anchorage, Alaska. Data collection included water, 

streambed sediments, lakebed sediments, and aquatic 

organisms samples from urban sites along the stream. 

Urban land use ranged from less than 1 percent of the 

basin above the furthest upstream site to 46 percent above 

the most downstream site. Findings suggest that water 

quality of Chester Creek declines in the downstream 

direction and as urbanization in the watershed increases. 

Water samples were collected monthly and during 

storms at a site near the stream’s mouth (Chester Creek 

at Arctic Boulevard) and analyzed for major ions and 

nutrients. Water samples collected during water year 1999 

were analyzed for selected pesticides and volatile organic 

compounds. Concentrations of fecal-indicator bacteria 

were determined monthly during calendar year 2000. 

During winter, spring, and summer, four water samples 

were collected at a site upstream of urban development 

(South Branch of South Fork Chester Creek at Tank Trail) 

and five from an intermediate site (South Branch of South 

Fork Chester Creek at Boniface Parkway).

Concentrations of calcium, magnesium, sodium, 

chloride, and sulfate in water increased in the downstream 

direction. Nitrate concentrations were similar at the three 

sites and all were less than the drinking-water standard. 

About one-quarter of the samples from the Arctic Boulevard site had concentrations of phosphorus that exceeded 

the U.S. Environmental Protection Agency (USEPA) 

guideline for preventing nuisance plant growth. Water 

samples collected at the Arctic Boulevard site contained 

concentrations of the insecticide carbaryl that exceeded 

the guideline for protecting aquatic life. Every water 

sample revealed a low concentration of volatile organic 

compounds, including benzene, toluene, tetrachloroethylene, methyl tert-butyl ether, and chloroform. No water 

samples contained volatile organic compounds concentrations that exceeded any USEPA drinking-water standard 

or guideline. Fecal-indicator bacteria concentrations in 

water from the Arctic Boulevard site commonly exceeded 

Federal and State guidelines for water-contact recreation.

Concentrations of cadmium, copper, lead, and zinc in 

streambed sediments increased in the downstream direction. Some concentrations of arsenic, chromium, lead, 

and zinc in sediments were at levels that can adversely 

affect aquatic organisms. Analysis of sediment chemistry 

in successive lakebed-sediment layers from Westchester 

Lagoon near the stream’s mouth provided a record of 

water-quality trends since about 1970. Concentrations of 

lead have decreased from peak levels in the mid-1970s, 

most likely because of removing lead from gasoline and 

lower lead content in other products. However, concentrations in recently-deposited lakebed sediments are still 

about 10 times greater than measured in streambed sediments at the upstream Tank Trail site. Zinc concentrations 

in lakebed sediments also increased in the early 1970s 

to levels that exceeded guidelines to protect aquatic life 

and have remained at elevated but variable levels. Pyrene, 

benz[a]anthracene, and phenanthrene in lakebed sediments 

also have varied in concentrations and have exceeded 

protection guidelines for aquatic life since the 1970s. 

Concentrations of dichloro-diphenyl-trichloroethane, 

polychlorinated biphenyls (PCBs), or their by-products 

generally were highest in lakebed sediments deposited in 

the 1970s. More recent sediments have concentrations that 

vary widely and do not show distinct temporal trends.

Tissue samples of whole slimy sculpin (Cottus 

cognatus), a non-migratory species of fish, showed concentrations of trace elements and organic contaminants. 

Of the constituents analyzed, only selenium concentrations showed levels of potential concern for protection of 

fish-eating wildlife and are most likely because of natural 

geologic sources. Although detected in sculpin, the total 

PCB concentration was less than the protection guideline 

for fish-eating wildlife.

The relative abundance of algae that are tolerant of 

increased salinity increased from the headwaters to the 

mouth, as did dissolved minerals in water. Pollution-sensitive benthic macroinvertebrate taxa decreased and dominance of pollution-tolerant worms increased in the downstream direction, indicating water-quality degradation. 

Abstract 1
Introduction

The National Water-Quality Assessment (NAWQA) 

Program was implemented in 1991 by the U.S. Geological Survey (USGS) to assess the status and trends in water 

quality for a large part of the Nation’s surface- and groundwater resources and to provide a better understanding of 

the factors that affect water quality (Gilliom and others, 

1995). The assessment of the Cook Inlet Basin, 1 of 51 

study units across the Nation, began in 1997. 

Understanding the effects of urbanization on water 

quality is a focus of the NAWQA Program. To help assess 

the effects of urban development on water quality in the 

Cook Inlet Basin, chemical, physical, and biological data 

were collected from sites along Chester Creek in Anchorage, Alaska, that represent a range of urban development 

intensity. Measurements were made to determine water 

chemistry in the stream; the presence of contaminants 

in streambed and lakebed sediments and in tissues of 

resident fish; the physical habitat within the stream; and 

the abundance and diversity of attached algae, benthic 

invertebrates, and fish living in the stream. This report 

summarizes the chemical analyses of water, bed-sediment, 

fish-tissue samples, and the biological communities in the 

Chester Creek watershed during 1998-2001. 

Most of the data summarized in this report were 

discussed or tabulated in various reports describing 

specific aspects of the assessment of water-quality conditions in the Cook Inlet Basin for the NAWQA program 

or in annual water-data reports for Alaska (Bertrand and 

others, 2000; Meyer and others, 2001; Meyer and others, 

2002). The environmental setting of the Cook Inlet Basin 

was described by Brabets and others (1999). The Chester 

Creek at Arctic Boulevard monitoring site was one of six 

routinely sampled sites in the Cook Inlet Basin. The water 

quality, biological, and physical-habitat conditions at 

these sites are described by Brabets and Whitman (2004). 

Water-quality data collected by USGS prior to 1998 and 

water-temperature data collected prior to 1999 in Chester 

Creek at Arctic Boulevard and other streams in the Cook 

Inlet Basin are summarized by Glass (1999) and Kyle and 

Brabets (2001). The occurrence and distribution of organic 

compounds and trace elements in streambed sediments 

and fish tissues in the Cook Inlet Basin were described by 

Frenzel (2000, 2002). The occurrence of fecal-indicator 

bacteria in Anchorage streams was described by Frenzel 

and Couvillion (2002). The effects of urbanization on macroinvertebrate communities in streams in Anchorage were 

discussed by Ourso (2001) and Ourso and Frenzel (2003).

Description of the Study Area

Chester Creek drains 28 square miles (mi2) in the central part of the Municipality of Anchorage in south-central 

Alaska (fig. 1). The stream originates along the Chugach 

Mountains front and flows to the west into the Knik Arm 

of Cook Inlet. The geology of the watershed consists primarily of metamorphic, volcanic, and igneous rock in the 

Chugach Mountains and unconsolidated alluvial and glacial deposits in the lower elevations (Brabets and others, 

1999). The land cover in the headwaters of the watershed 

consists of shrubs, tundra, forests, and wetlands (fig. 2) 

and is part of the U.S. Army’s Fort Richardson. The 

lower portion of the watershed is used primarily for urban 

purposes, including residential, commercial, institutional 

(schools and hospitals), and transportation (roads and a 

municipal airport) uses. Land cover within the watershed 

during 2000 consisted of approximately 46 percent urban, 

32 percent forest, 17 percent shrub or tundra, and 4 percent 

wetland or water (Brabets and Whitman, 2004). About 

78,000 people lived within the watershed during 2000, 

making it one of the most densely populated watersheds in 

Alaska. 

The stream, its water impoundments (Westchester 

Lagoon and University Lake, fig. 3), and parks and trails 

adjacent to the stream are extensively used for recreation 

by area residents and visitors. The stream historically supported large runs of coho salmon in which several thousand adults returned to spawn (Whitman, 2002). Several 

government agencies and nongovernment organizations 

are proposing projects to improve fish passage and the 

conditions of instream and riparian areas to help restore 

salmon populations. Water from the stream is not used 

directly for drinking-water supply, but the stream recharges 

aquifers from which nearby public-supply and domestic 

wells obtain their water. Chester Creek has three major 

tributaries. The north and middle forks are in the northcentral part of the watershed and drain mostly residential 

and commercial areas (fig. 2). Much of these streams have 

been rerouted through underground pipes and straightened 

drainage channels. The south fork is the longest tributary and originates on the western slope of the Chugach 

Mountains in a relatively undeveloped portion of the Fort 

Richardson military reservation. Near the center of the 

watershed, the south fork flows through a former gravel pit 

on a college campus and forms a 37-acre lake, University 

Lake. Beaver dams are present downstream from the lake. 

Hillstand Pond is formed by a channel constriction below 

Lake Otis Parkway and is downstream of the confluence of 

the middle and south forks. Westchester Lagoon is formed 

by a weir near the stream’s mouth. Although greenbelts 

and parks parallel much of the main stem and some of 

the north, middle, and south forks, there are several areas 

where residential properties extend to the water’s edge. 

The greenbelts and parklands provide buffers of riparian 

   
or wetland vegetation along much of the stream and help 

intercept runoff of sediment and chemicals from urban 

areas, provide bank stability, and provide shading and habitat for aquatic and terrestrial animals. However, numerous 

storm drains empty directly into the creek, bypassing these 

vegetated buffer zones. 

The climate of the Chester Creek watershed is transitional between continental and maritime (Brabets and 

others, 1999). Average annual air temperature, measured 

Description of the Study Area 

67 66

27

Ship Creek Basin Campbell Creek Basin Little Rabbit Creek Basin

Chester Creek Basin Rabbit Creek Basin Sampling site

Knik Arm

Turnagain Arm

Cook

Inlet

EXPLANATION

Chester Creek

Chester Creek Watershed

27

149o59'

61o21'

61o

149o14'

0

0 5

5

10 KILOMETERS

10 MILES

ALASKA

Anchorage

A B

Figure 1.  Major streams in the metropolitan area of Anchorage, Alaska. 
 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

EXPLANATION

Medium to High Density Residental

Rural to Low Density Residental

Commercial

Extractive

Road

Institutional

Urban Vegetation

Needleleaf Forest

Mixed Forest

Shrub and Graminoid

Lake and Pond

Wetland

Urban Barren Tall, Low, and Dwarf Shrub and Barren Ground

0

0

1

1 2

2 3 MILES

3 KILOMETERS

South Bra nch South Fork Chester Cr

North Fork

Chester Cr

Middle Fork

Chester Cr

61o

13'

149o

53'

61o

11'

149o

53'

61o

13'

149o

37'

61o

10'

149o35'

A

67

66

B

27

Sampling Site

Figure 2.  Land cover in the Chester Creek watershed during 2000.

South Bra nch South Fork Chester Cr

North Fork Chester Cr

Middle Fork Chester Cr

 Chester Cr

Westchester

Lagoon Hillstrand

Pond

0

0

1

1 2

2 3 MILES

3 KILOMETERS

A

67

66

N

B

27

15th Ave

Glenn Highway

Northern Lights Blvd

Tudor Rd

36th Ave

DeBarr Ave

Muldoon Rd

Bonif

Br

ace Pkwy

agaw St

Lake Otis Pkwy

C St

Goose

Lake

Se

ward Hwy

Minnesota Dr

University

Lake

Sampling site

Figure .  Sampling sites in the Chester Creek watershed, 1998-2001. See Table 1.
at the Ted Stevens Anchorage International Airport about 

3 mi. southwest of the watershed, is about 37°F, based 

on the 30-year period from 1971 through 2000. Mean 

monthly temperatures at the airport range from a low 

of 17°F in January to a high of 59°F in July. Precipitation averages 16.0 inches per year (in/yr) at the airport, 

but may be 25 in/yr or more at higher elevations in the 

stream’s headwater area. Precipitation measured at the 

airport for water years 1999-2001 was near normal during 

1999 and 2000 and below normal in 2001—16.1, 16.3, 

and 13.7 inches, respectively. Generally, about half of the 

precipitation falls during July through October as rain. 

Precipitation from November through March is usually 

as snow. Snow remains on the land surface and ice covers 

much of the stream from November through March.

Human activities have affected the timing of water 

runoff and surface-water quality in the watershed (Barnwell and others, 1972; Brabets, 1987). The conversion of 

forests and wetlands to urban uses and the channelizing, 

straightening, and lowering of streams have caused more 

rapid rises and declines in streamflows. Runoff from roads, 

parking lots, and yards, and emissions from vehicles have 

increased the concentrations of many contaminants in 

stream water—including road deicing salts, trace elements, 

insecticides, petroleum products, and bacteria. Chester 

Creek, University Lake, and Westchester Lagoon have 

been classified as water-quality impaired by the Alaska 

Department of Environmental Conservation (1998) due to 

high concentrations of fecal-coliform bacteria.

Data Collection and Analysis

An integrated monitoring program was conducted 

that included collection of water, sediment, fish tissue, 

and aquatic organisms to help obtain an understanding of 

urban influences on stream health. Samples were collected 

for this study in accordance with methods required by 

the NAWQA Program (U.S. Geological Survey, 1997 to 

present; U.S. Geological Survey, 2002; Shelton, 1994; and 

Shelton and Capel, 1994).

Three water, streambed-sediment, and ecologicalassessment monitoring sites and two lakebed sediment 

sites (fig. 3 and table 1) were established in the Chester 

Creek watershed to represent a range of urban intensity. Chester Creek at Arctic Boulevard (termed “Arctic 

Boulevard” and numbered 27) and Westchester Lagoon 

(site A) are near the stream’s mouth. About half of the 

area upstream of these two sites is used for residential, 

commercial, institutional, and transportation uses. South 

Branch of South Fork Chester Creek at Tank Trail (termed 

“Tank Trail” and numbered 66 in this and previous reports 

for the Cook Inlet Basin NAWQA program) is on the 

Fort Richardson Army Reservation and is upstream of 

urban development. South Branch of South Fork Chester 

Creek at Boniface Parkway (termed “Boniface Parkway” 

and numbered 67) is downstream from the Tank Trail 

site. Forests, shrubs, and wetlands cover the upper 12 mi2

of Boniface Parkway’s basin, whereas landcover in the 

3 mi2 immediately upstream of this site consists mostly of 

residential urban development. Hillstrand Pond (site B) 

incorporates a drainage area of 20 mi2.

Water

The Arctic Boulevard site was one of six intensively 

sampled sites (termed fixed sites) in the Cook Inlet Basin 

NAWQA study (Brabets and Whitman, 2004). At each 

fixed site, water samples were collected in January and 

March and monthly from April or May to November 

and analyzed for dissolved ions, nutrients, dissolved and 

suspended organic carbon, and suspended sediment. Field 

measurements of specific conductance, pH, water temperature, dissolved oxygen (DO), alkalinity, and bicarbonate 

Data Collection and Analysis 

Table 1.  Sampling sites in the Chester Creek watershed, 1998-2001.

[Sample type: BS, streambed sediment; BSC, cores of lakebed sediments; E, ecological assessment; T, fish tissue; W, water chemistry; --, no data]

Site 

No.

(from 

fig. 1)

Site Name USGS Station 

Number Latitude Longitude Sample Type

Basin 

Size 

(square

miles)

Urban Land 

Cover within 

basin 

(percent)

66 South Branch of South Fork Chester 

Creek at Tank Trail 15274796 61°11’25” 149°42’13” BS, E, W 4.3 <1

67 South Branch of South Fork Chester 

Creek at Boniface Parkway 15274830 61°11’23” 149°46’33” BS, E, W 14.8 20

B

Hillstrand Pond below Lake Otis 

Parkway 611202149502000 61°12’02” 149°50’20” BSC 20 --

27 Chester Creek at Arctic Boulevard 15275100 61°12’19” 149°53’43” BS, E, T, W 27.4 46

A Westchester Lagoon above Minnesota 

Drive 611226149544601 61°12’16” 149°54’28” BSC 28 --
were completed according to NAWQA protocols (Shelton, 

1994; Wilde and Radtke, 1998). Instantaneous discharge 

was obtained from a continuous-recording streamflow 

gage at the site in accordance with standard USGS procedures (Rantz and others, 1982). In addition to the fixed-site 

sampling constituents, selected pesticides and volatile 

organic compounds (VOCs) were analyzed monthly during water year 1999, and concentrations of fecal-indicator bacteria were determined monthly during calendar 

year 2000. Measurements of specific conductance were 

recorded continuously from June 2000 through September 

2001. Measurements of water temperature were recorded 

continuously from October 1998 through September 2001 

at each of the three water-monitoring sites.

Water samples from the Tank Trail and Boniface 

Parkway sites were collected less frequently (five or fewer 

times) than from the Arctic Boulevard site. Samples for 

dissolved ions, nutrients, dissolved and suspended organic 

carbon, suspended sediment, and fecal-indicator bacteria 

were collected in winter, spring, and summer. Field measurements of specific conductance, pH, water temperature, 

DO, alkalinity, and bicarbonate were made each time water 

samples were collected. No water samples from these two 

upstream sites were analyzed to determine concentrations 

of pesticides or VOCs.

Most water samples were obtained by collecting 

depth-integrated subsamples at equal-width increments 

across the stream channel by wading (Shelton, 1994). 

A weighted-bottle sampler was used separately to collect dissolved and suspended organic-carbon samples in 

a baked amber glass bottle at the midpoint in the stream. 

Water samples for VOC analysis were collected with a 

specially designed Wildco sampler at the midpoint in the 

stream (Shelton, 1997). Lipid-containing semipermeable 

membrane devices (SPMDs) were also used to determine 

the presence of pesticides, VOCs, and semivolatile organic 

compounds (SVOCs) in water at the Arctic Boulevard site. 

The SPMDs are passive in situ water samplers that mimic 

the uptake of contaminants by biota (Huckins and others, 1993). Three SPMDs were placed in stream water at 

the Arctic Boulevard site from May 18 to July 13, 2000. 

Uptake by SPMDs indicates the compounds were dissolved in the water, and therefore, there was potential 

exposure for aquatic organisms at the site. Concentrations 

of organic compounds in the water column were estimated 

from extracts from the SPMDs.

Water samples were processed in the field according to NAWQA protocols (Shelton, 1994). A cone splitter 

was used to composite most of the samples into Teflon 

bottles. Samples analyzed for dissolved ions, nutrients, and 

field alkalinity were filtered through a 0.45-μm pore-size 

capsule filter. Samples analyzed for dissolved and suspended organic carbon were filtered through a 0.45-μm 

pore-size silver filter, and samples analyzed for pesticides 

were filtered through a 0.7-μm pore-size glass-fiber filter. 

Suspended-sediment samples were collected and processed 

according to methods described by Edwards and Glysson (1988) and shipped to the USGS Sediment Laboratory in Louisville, Ky., for particle-size and concentration 

analysis. All other water-quality samples were shipped to 

the USGS National Water-Quality Laboratory (NWQL) 

in Denver, Colo., for analysis using methods described by 

Fishman (1993), Sandstrom and others (1992), Zaugg and 

others (1995), and Furlong and others (1996). 

Summary statistics for field parameters and concentrations of inorganic constituents include the number 

of analyses and the minimum, median, and maximum 

values measured. When more than one field value or 

concentration of inorganic constituent was reported in a 

day at a site, the median value for that day was used to 

determine the summary statistics. For organic constituents, only compounds that were detected are listed, along 

with the number of analyses, the number of times the 

compound was detected, and the maximum concentration. Concentrations that were estimated or less than the 

method-detection limit are marked with an “E”. Comparisons are made with drinking-water standards and 

guidelines established by the U.S. Environmental Protection Agency (USEPA) and guidelines for the protection 

of aquatic life set by the Canadian Council of Ministers 

of the Environment (2002b). A maximum contaminant 

level (MCL) is the maximum allowable concentration of 

a contaminant in water delivered to any user of publicwater systems (USEPA, 2002). The MCLs are enforceable 

standards based on an average concentration taken from 

four quarterly samples of finished (treated) drinking water. 

A Lifetime Health Advisory (HAL) is a nonenforceable, 

risk-based guideline below which no short- or long-term 

human-health effects are expected, based on drinking a 

specific amount of water for a specific period of time. 

Probable effect levels (PELs) are used to indicate contaminant concentrations in water or freshwater sediment 

associated with adverse effects on aquatic life. The PEL 

is an estimate of the concentration levels above which 

adverse biological effects occur frequently. Standards 

and guidelines to evaluate the potential adverse effects of 

organic compounds in water have limitations because not 

all organic compounds or their breakdown products have 

standards or guidelines, and the standards and guidelines 

are based on toxicity tests on a single compound and do 

not evaluate the additive or synergistic effects of multiple 

compounds.

Sediment

Samples of recently-deposited streambed sediments 

were collected at least once from depositional areas near 

each water-monitoring site and analyzed for selected 

trace elements and organic contaminants using techniques 

described by Shelton and Capel (1994). The top 2 cm of 

sediment were collected from several areas and compos-

 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001
ited to form a large sample volume. Streambed sediments 

were wet sieved so that only particles finer than 0.063 mm 

(the silt and clay fractions) were analyzed for trace elements and only particles finer than 2 mm (the sand, silt, 

and clay fractions) were analyzed for organic contaminants. Sediments were digested in strong acid prior to 

analysis by the NWQL. One unsieved streambed-sediment 

sample was collected from the Arctic Boulevard site on 

May 13, 1998, and was analyzed by the USGS Columbia 

Environmental Research Laboratory in Columbia, Mo., to 

determine concentrations of total mercury and methylmercury (Brumbaugh and others, 2001). Concentration data 

are reported on a dry-weight basis in micrograms per gram 

(μg/g) for trace elements and micrograms per kilogram 

(μg/kg) for organic compounds. 

Cores of lakebed sediments from two impoundments 

on Chester Creek, Hillstrand Pond (site B in fig. 3) and 

Westchester Lagoon (site A), were collected and segments 

from each core sample were analyzed for selected trace 

elements and organic contaminants (P.C. VanMetre, U.S. 

Geological Survey, written commun., 2001). Analyses of 

individual layers of lakebed sediments were performed on 

bulk (whole) samples. 

Concentrations of contaminants in sediments are 

compared to guidelines for the protection of aquatic life set 

by the Canadian Council of Ministers of the Environment 

(2002a, 2002b). The PELs are established for eight of the 

trace elements and 18 of the organochlorine and semivolatile organic compounds analyzed. These sediment guidelines are based on bulk (whole) sediment samples. For this 

study, analyses of lakebed sediments were performed on 

bulk samples, whereas streambed sediments were sieved 

so that only particles finer than 0.063 mm were analyzed 

for trace elements and only particles finer than 2 mm were 

analyzed for organic contaminants. Some trace elements 

and organic compounds attach strongly to fine-grained 

sediment, thus their concentrations are expected to be 

higher in sieved streambed samples than in bulk samples 

and their toxicity may be overestimated.

Fish Tissue

Slimy sculpin, Cottus cognatus, were collected in 

1998 and 1999 near the Arctic Boulevard site and composite samples of whole fish were analyzed for selected trace 

elements and organic contaminants. Concentration data are 

reported on a wet-weight basis in μg/g for trace elements 

and μg/kg for organic compounds. For contaminants in 

whole fish, comparisons with the New York fish-flesh 

criteria for protection of fish-eating wildlife (Newell and 

others, 1987) are used. These animal-tissue guidelines are 

intended to protect wildlife from adverse effects other than 

cancer, such as mortality, reproductive impairment, and 

organ damage. Wildlife guidelines from the State of New 

York were used because no comparable national guidelines 

are available for a large number of contaminants.

Aquatic Communities

An inventory of instream and riparian characteristics 

was conducted along a 300- to 500-ft-long reach near each 

water-quality site using methods described by Fitzpatrick 

and others (1998). Measures of instream habitat were 

made along 11 transects perpendicular to the streamflow 

and at approximately equal intervals within each of the 

three reaches. Attached algae, benthic macroinvertebrates, 

and fish were collected within each reach to determine the 

spatial distributions and community structures of these 

aquatic species using methods described in Porter and others (1993), Cuffney and others (1993), Meador and others 

(1993), and Moulton and others (2002).

Water-Quality Characteristics

Summary statistics for selected water-quality field 

measurements and inorganic constituents analyzed for 

each site are presented in table 2 and discussed in the following sections. Streamflow conditions at the Arctic Boulevard site are described briefly and compared to historical 

mean streamflows.

Streamflow

Streamflow often affects the water-quality conditions of a stream. During high flows, concentrations of 

some water-quality constituents may decrease as a result 

of dilution or increase as a result of inputs from stormwater runoff. A hydrograph showing daily mean streamflow 

for the sampling period and the sampling dates for the 

Arctic Boulevard site is presented in figure 4. Streamflows 

in Chester Creek are high from April through October 

due to runoff from snowmelt and rain and are low during 

winter. The mean annual discharge for the watershed site 

is 20.2 cubic feet per second (ft3/s), based on records collected intermittently from 1966 through 2001 at the Arctic 

Boulevard site. Annual discharges during water years 

1999-2001 were 20.0, 25.7, and 20.5 ft3/s, respectively. 

Field Measurements

Water temperatures in Chester Creek are reflective 

of climatic and local physical conditions, such as shading. Figure 5 shows daily mean water temperatures at 

the Arctic Boulevard site. Temperatures were cooler at 

the two upstream sites. For water year 2001, mean water 

Water-Quality Characteristics 
temperatures at the Tank Trail, Boniface Parkway, and 

Arctic Boulevard sites were 3.1, 4.4, and 5.9°C, respectively. State water-quality standards (Alaska Department 

of Environmental Conservation, 2003) require that water 

temperatures in streams used by fish are not to exceed 

15°C in migration routes or in rearing areas and temperatures are not to exceed 13°C in spawning areas and during 

egg and fry incubation periods. Daily maximum water 

temperatures were as great as 17°C at the Arctic Boulevard 

site and 15°C at the Boniface Parkway site, indicating that 

there may be occasional stress to fish from elevated stream 

temperatures.

Specific conductance is a measure of the capacity 

of a sample of water to conduct electricity and is proportional to the concentration of the charged ion species in the 

water and to the concentration of dissolved solids of the 

water. The concentrations of dissolved solids and values of 

specific conductance increased from the stream’s headwaters to its mouth. For example, during a low-flow period in 

mid-March 2000, concentrations of dissolved solids (sum 

of constituents) at the Tank Trail, Boniface Parkway, and 

Arctic Boulevard sites were 80, 112, and 156 milligrams 

per liter (mg/L), respectively, and specific conductance 

values were 122, 211, and 272 microsiemens per centimeter at 25°C (μS/cm), respectively. Specific conductance 

and concentrations of dissolved solids at the Tank Trail 

site did not vary appreciably, ranging from 109 to 129 

μS/cm and 68 to 80 mg/L, respectively, whereas values 

of specific conductance and concentrations of dissolved 

solids at the lower two sites had greater variations that 

changed with changes in stream discharge. During snowmelt, specific conductance at the Arctic Boulevard site 

generally increased with increasing streamflow (fig. 6) 

due to the flushing of surface contaminants, such as road 

deicing salts, into the stream. The daily mean specific 

conductance at the Arctic Boulevard site was as great as 

668 μS/cm on January 15, 2001. During summer rains, 

specific conductance commonly decreased with increasing streamflow due to dilution.

Stream water in Chester Creek is alkaline as median 

pH values ranged from 7.5 to 7.9 units at the three sites 

(table 2). Stream water was well oxygenated at all sites. 

Concentrations of DO at the Arctic Boulevard site ranged 

from 9.2 to 14.6 mg/L, with saturation ranging from 79 to 

113 percent.

Inorganic Constituents

Calcium and bicarbonate were typically the dominant cation and anion, respectively, in Chester Creek 

stream water. The use of sodium chloride and magnesium 

chloride as road deicing salts increased the amount of 

these ions in stream water, as can be seen in the ionic 

compositions of snowmelt runoff at the Arctic Boulevard 

site (fig. 7). In each of the three panels of the trilinear diagram, results from the water samples collected 

March 26 and 27, 1999, are located to the right of samples 

collected at other times, indicating higher proportions 

   

1

2

5

10

20

50

300

O N D

1998 1999

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

2000

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

2001

J F M A M J J A S

Daily mean discharge

Discharge when 

water sample collected

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

200

100

Water Year 1999 Water Year 2000 Water Year 2001

Figure .  Discharge hydrograph for Chester Creek from gage at Arctic Blvd. showing time distribution and 

flow distribution of water samples.
Water-Quality Characteristics 9

Table 2.  Statistical summary of selected water-quality data from Chester Creek, 1998-2001.

[When more than one value was reported in a day at a site, the median value for that day was used to determine these summary statistics. Number in 

parenthesis is the number used by both USEPA and USGS to identify that parameter in computerized data bases. Abbreviated site names: Tank Trail, 

South Branch of South Fork Chester Creek at Tank Trail; Boniface Parkway, South Branch of South Fork Chester Creek at Boniface Parkway; Arctic 

Bouelvard, and Chester Creek at Arctic Boulevard. mg/L, milligram per liter; μg/L, microgram per liter; cols/100 ml, bacteria colonies per 100 millileter; <, less than; E, estimated]

Constituent Abbreviated Site Name

Value or Concentration

Number of 

Analyses Minimum Median Maximum

Stream Discharge 

Instantaneous discharge, in cubic feet per second (00061) Tank Trail 6 2.2 3.8 6.4

Boniface Parkway 5 8.9 13.0 23.0

Arctic Boulevard 49 6.3 23.0 122.0

Field Measurements

Water temperature, in degrees Celsius (00010) Tank Trail 7 1.0 6.6 7.5

Boniface Parkway 5 1.5 8.0 10

Arctic Boulevard 49 0.0 3.5 15.4

Specific conductance, in microsiemens per centimeter 

(00095)

Tank Trail 6 109 115 129

Boniface Parkway 5 132 188 217

Arctic Boulevard 49 120 261 480

Dissolved oxygen, in mg/L (00300) Tank Trail 7 11.0 11.4 13.9

Boniface Parkway 4 10.2 11.1 12.4

Arctic Boulevard 49 9.2 12 15

Dissolved oxygen saturation, in percent (00301) Tank Trail 5 89 93 102

Boniface Parkway 4 79 91 97

Arctic Boulevard 48 79 96 110

pH, in pH units (00400) Tank Trail 7 7.5 7.9 8.2

Boniface Parkway 5 7.3 7.5 8.2

Arctic Boulevard 49 7.1 7.8 8.6

Hardness, in mg/L as CaCO3 (00900) Tank Trail 4 52 56 62

Boniface Parkway 5 54 77 85

Arctic Boulevard 44 48 110 130

Inorganic Constituents 

Calcium, dissolved, in mg/L (00915) Tank Trail 4 15.9 17.4 18.9

Boniface Parkway 5 16.6 23.4 25.4

Arctic Boulevard 49 14 32 37

Magnesium, dissolved, in mg/L (00925) Tank Trail 4 2.9 3.3 3.6

Boniface Parkway 5 3.2 4.6 5.3

Arctic Boulevard 49 3.1 7.5 14.7

Sodium, dissolved, in mg/L (00930) Tank Trail 4 1.7 1.8 1.9

Boniface Parkway 5 2.5 5.9 8.2

Arctic Boulevard 49 3.9 8.0 35

Acid neutralizing capacity, in mg/L (00410) Tank Trail 3 39 50 51

Boniface Parkway 5 50 62 63

Arctic Boulevard 46 31 78 100
10 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

Table 2.  Statistical summary of selected water-quality data from Chester Creek, 1998-2001.—Continued

[When more than one value was reported in a day at a site, the median value for that day was used to determine these summary statistics. Number in 

parenthesis is the number used by both USEPA and USGS to identify that parameter in computerized data bases. Abbreviated site names: Tank Trail, 

South Branch of South Fork Chester Creek at Tank Trail; Boniface Parkway, South Branch of South Fork Chester Creek at Boniface Parkway; Arctic 

Bouelvard, and Chester Creek at Arctic Boulevard. mg/L, milligram per liter; μg/L, microgram per liter; cols/100 ml, bacteria colonies per 100 millileter; <, less than; E, estimated]

Constituent Abbreviated Site 

Name

Value or Concentration

Number of 

Analyses Minimum Median Maximum

Inorganic Constituents—Continued 

Potasium, dissolved, in mg/L (00935) Tank Trail 4 0.2 0.3 0.5

Boniface Parkway 5 0.5 0.6 3

Arctic Boulevard 49 0.8 1 5

Bicarbonate, in mg/L as HCO3 (00453) Tank Trail 3 46 54 56

Boniface Parkway 5 60 73 80

Arctic Boulevard 49 43 94 120

Alkalinity, field incremental titration, in mg/L as 

CaCO3 (39086)

Tank Trail 3 38 48 50

Boniface Parkway 5 49 61 65

Arctic Boulevard 49 21 77 100

Sulfate, dissolved, in mg/L (00945) Tank Trail 4 9.3 11.6 12.9

Boniface Parkway 5 9.2 13.8 16.6

Arctic Boulevard 49 8.7 21 27

Chloride, dissolved, in mg/L (00940) Tank Trail 4 0.3 0.6 0.7

Boniface Parkway 5 2.6 9.6 15.6

Arctic Boulevard 49 6.6 16 94

Fluoride, dissolved, in mg/L (00950) Tank Trail 4 <0.1 <0.1 <0.1

Boniface Parkway 5 <0.1 <0.1 <0.1

Arctic Boulevard 49 <0.1 <0.1 <0.1

Silica, dissolved, in mg/L as SiO2 (00955) Tank Trail 4 9.8 10.4 11.7

Boniface Parkway 5 7.0 10.1 11.7

Arctic Boulevard 49 5.4 10.3 13.5

Nitrite, dissolved in mg/L as N (00613) Tank Trail 4 <0.001 0.001 0.001

Boniface Parkway 5 <0.001 0.004 0.011

Arctic Boulevard 49 0.001 0.006 0.069

Nitrite plus nitrate, dissolved, in mg/L as N (00631) Tank Trail 4 0.37 0.5 1.02

Boniface Parkway 5 0.341 0.5 0.578

Arctic Boulevard 49 0.005 0.62 0.91

Ammonia, dissolved, in mg/L as N (00608) Tank Trail 4 <0.002 <0.002 0.004

Boniface Parkway 5 <0.002 0.005 0.392

Arctic Boulevard 49 0.002 0.024 0.48

Nitrogen, total ammonia plus organic, in mg/L as N 

(00625)

Tank Trail 4 E0.06 0.07 0.23

Boniface Parkway 5 0.12 0.3 1.1

Arctic Boulevard 49 0.08 0.24 2.40

Nitrogen, dissolved ammonia plus organic, in mg/L 

as N (00623)

Tank Trail 4 <0.1 0.1 0.21

Boniface Parkway 5 E0.08 0.2 0.73

Arctic Boulevard 49 0.068 0.17 1.26

Total phosphorus, in mg/L as P (00665) Tank Trail 4 0.008 0.01 0.022

Boniface Parkway 5 0.008 0.026 0.171

Arctic Boulevard 49 0.004 0.020 0.590
Water-Quality Characteristics 11

Table 2.  Statistical summary of selected water-quality data from Chester Creek, 1998-2001.—Continued

[When more than one value was reported in a day at a site, the median value for that day was used to determine these summary statistics. Number in 

parenthesis is the number used by both USEPA and USGS to identify that parameter in computerized data bases. Abbreviated site names: Tank Trail, 

South Branch of South Fork Chester Creek at Tank Trail; Boniface Parkway, South Branch of South Fork Chester Creek at Boniface Parkway; Arctic 

Bouelvard, and Chester Creek at Arctic Boulevard. mg/L, milligram per liter; μg/L, microgram per liter; cols/100 ml, bacteria colonies per 100 millileter; <, less than; E, estimated]

Constituent Abbreviated Site 

Name

Value or Concentration

Number of 

Analyses Minimum Median Maximum

Inorganic Constituents—Continued 

Phosphorus, dissolved, in mg/L asP (00666) Tank Trail 4 <0.004 E0.004 E0.005

Boniface Parkway 5 E0.004 0.004 0.082

Arctic Boulevard 49 0.002 0.006 0.21

Orthophosphorus, dissolved, in mg/L as P (00671) Tank Trail 4 <0.001 0.003 0.006

Boniface Parkway 5 <0.001 0.002 0.057

Arctic Boulevard 49 0.001 0.004 0.094

Dissolved solids, residue at 180 degrees Celsius, in mg/L 

(70300)

Tank Trail 4 76 85 89

Boniface Parkway 5 83 123 129

Arctic Boulevard 49 72 160 279

Dissolved solids, sum of constituents, in mg/L (70301) Tank Trail 4 68 75 80

Boniface Parkway 5 78 103 116

Arctic Boulevard 49 66 145 248

Iron, dissolved, in μg/L (01046) Tank Trail 3 <10 <10 <10

Boniface Parkway 5 60 160 240

Arctic Boulevard 49 30 100 520

Manganese, dissolved, in μg/L (01056) Tank Trail 4 <2.0 <2.2 <3.0

Boniface Parkway 5 29.7 69.9 139

Arctic Boulevard 49 32 75 215

Total organic particulate carbon, in mg/L as C (00689) Tank Trail 3 <0.2 0.2 0.3

Boniface Parkway 4 0.2 2.0 3.9

Arctic Boulevard 49 0.2 0.6 5

Organic carbon, dissolved, in mg/L (00681) Tank Trail 4 1.0 1.7 2.7

Boniface Parkway 5 1.6 3.9 6.8

Arctic Boulevard 49 1.5 2.5 7.9

Total inorganic plus organic carbon, in mg/L as C 

(00694)

Boniface Parkway 1 5.2 5.2 5.2

Arctic Boulevard 15 0.5 1.1 5.1

Suspended Sediment

Suspended sediment, in mg/L (80154) Tank Trail 3 3 4 6

Boniface Parkway 4 4 24 50

Arctic Boulevard 49 1 9 322

Suspended sediment finer than 0.062 mm, in percent 

(70331)

Tank Trail 1 26 26 26

Boniface Parkway 3 86 89 96

Arctic Boulevard 23 55 92 97

Fecal-Indicator Bacteria

E. coli bacteria, in cols/100 ml (31633) Tank Trail 3 <1 <1 E5

Boniface Parkway 3 67 350 700

Arctic Boulevard 16 E20 148 E1500
12 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

of sodium and chloride in the water. The water sample 

collected on March 26, 1999, had a specific conductance 

value of 480 μS/cm and a dissolved-solids concentration 

of 248 mg/L, with 34 mg/L of sodium (approximately 35 

percent of the cations were sodium, when concentrations 

are expressed in milliequivalents per liter) and 94 mg/L of 

chloride (about 60 percent of the anions were chloride). 

Median concentrations of chloride and sodium increased 

in the downstream direction indicating the influence of 

urbanization.

Nitrogen and phosphorus are essential nutrients for 

a healthy aquatic ecosystem because they help regulate 

the productivity of organisms in freshwater systems. 

However, excessive amounts of nitrogen and phosphorus 

can adversely affect surface-water quality through eutrophication (excessive aquatic-plant growth) and toxicity 

to aquatic life. Concurrent measurements of nitrite-plusnitrate concentrations at the three sites were similar. 

Almost all concentrations were less than one-tenth of the 

USEPA’s drinking-water standard of 10 mg/L for nitrate. 

Table 2.  Statistical summary of selected water-quality data from Chester Creek, 1998-2001.—Continued

[When more than one value was reported in a day at a site, the median value for that day was used to determine these summary statistics. Number in 

parenthesis is the number used by both USEPA and USGS to identify that parameter in computerized data bases. Abbreviated site names: Tank Trail, 

South Branch of South Fork Chester Creek at Tank Trail; Boniface Parkway, South Branch of South Fork Chester Creek at Boniface Parkway; Arctic 

Bouelvard, and Chester Creek at Arctic Boulevard. mg/L, milligram per liter; μg/L, microgram per liter; cols/100 ml, bacteria colonies per 100 millileter; <, less than; E, estimated]

Constituent Abbreviated Site Name

Value or Concentration

Number of 

Analyses Minimum Median Maximum

Fecal-Indicator Bacteria—Continued

Enterococci bacteria, in cols/100 ml (31649) Tank Trail 3 <1 4 30

Boniface Parkway 2 87 1228 2370

Arctic Boulevard 17 29 180 3400

Fecal-coliform bacteria, in cols/100 ml (31625) Tank Trail 4 <1 4 E7

Boniface Parkway 2 90 395 E700

Arctic Boulevard 18 E17 280 1994

Water Year 1999 Water Year 2000 Water Year 2001

-20

0

2

4

6

8

10

12

14

16

WATER TEMPERATURE, IN DEGREES CELSIUS

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

No

Record

1998 1999 2000 2001

Figure .  Daily mean water temperature for Chester Creek at Arctic Boulevard, water years 1999 to 2001.
Nitrate concentrations at the Arctic Boulevard site generally decreased with increasing discharge and generally 

were higher during winter than summer. These results 

suggest that ground-water discharge may be a significant 

contributor of nitrate and/or that nitrate is not taken up by 

plant life and converted to other forms of nitrogen during 

winter. Possible sources of nitrate to the ground-water and 

stream systems include animal wastes, fertilizers applied 

to lawns, effluent from septic systems or leaky sewer lines, 

and nitrogen-fixing plants such as alder and clover. In contrast to nitrate’s inverse relation with discharge, concentrations of total nitrogen (ammonia plus organic nitrogen) 

typically increased during snowmelt and rainfall runoff 

(fig. 8). The highest total ammonia plus organic nitrogen 

value observed in Chester Creek during this study was 

2.40 mg/L on April 17, 1999, during snowmelt runoff.

Twenty-six percent of the total phosphorus concentrations measured at the Arctic Boulevard site exceeded 

0.1 mg/L, the USEPA desired (maximum) goal for preventing nuisance plant growth in streams (USEPA, 1986a). 

Elevated phosphorus concentrations were associated with 

the transport of suspended sediment. The maximum value 

observed, 0.59 mg/L, was during runoff from snowmelt on 

April 17, 1999, when discharge was 38 ft3/s and the suspended-sediment concentration was 322 mg/L, the highest 

suspended-sediment concentration observed during this 

study. Concentrations of dissolved orthophosphate were 

low, the median of 45 samples collected was 0.004 mg/L 

and the maximum value was 0.094 mg/L, indicating that 

inorganic suspended phosphorus is the primary form of 

total phosphorus in the water. 

Fecal-Indicator Bacteria

Sixteen to 18 water samples were collected from 

the Arctic Boulevard site and analyzed to determine 

concentrations of fecal coliform, Escherichia coli (E. 

coli), and enterococci bacteria (Frenzel and Couvillion, 

2002). Fecal coliform and E. coli are indicator organisms 

and two species of bacteria in the total coliform group. 

Although fecal coliforms may originate in the intestines 

of warm-blooded animals and humans, they have also 

been found in non-fecal sources. E. coli originates in 

the intestines warm-blooded animals and humans and 

provides specific evidence of fecal contamination from 

warm-blooded animals. Enterococci are a subgroup of 

the fecal-streptococci bacteria, but are a more specific 

indicator of fecal contamination in water than fecal-streptococci bacteria (Francy and others, 2000). The presence 

of E. coli and enterococci bacteria is evidence that fecal 

contamination has occurred and increases the concern that 

disease-causing organisms are present in the water. The 

USEPA recommends sampling of E. coli and enterococci 

bacteria in recreational-use water because studies show 

statistically significant relations between concentrations 

of those indicator bacteria and gastrointestinal illness in 

swimmers (USEPA, 1986a). Recommended guidelines 

Water-Quality Characteristics 1

Discharge

Specific Conductance

10

15

20

30

40

50

60

80

100

150

200

300

400

500

600

800

1000

Oct

14 28

Nov

14 28

Dec

14 28

2000 2001

Jan

14 28

Feb

14 28

Mar

14 28

Apr

14 28

May

14 28

Jun

14 28

Jul

14 28

Aug

14 28

Sep

14 28

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER 

CENTIMETER AT 25 DEGREES CELSIUS

Figure .  Specific conductance and daily discharge for Chester Creek at Arctic Boulevard, water year 2001.
1 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

SULFATE PLUS CHLORIDE

CALCIUM PLUS MAGNESIUM

BICARBONATE

SODIUM PLUS POTASSIUM

MAGNESIUM

CALCIUM

PERCENT

CHLORIDE, FLUORIDE, NITRITE PLUS NITRATE

SULFATE

PERCENT

PERCENT

3/26/99

3/27/99

0 

20 

40 

60 

80 

100 

0 

20 

40 

60 

80 

100 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

0 

20 40 

60 

80 

100 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

100 80 60 40 20 

 0 

0 

20 

40 

60 

80 

100 0 

20 

40 

60 

80 

100 

Figure .  Trilinear diagram showing the major-ion compositions of 49 water samples 

collected from Chester Creek at Arctic Boulevard, water years 1999-2001.

O N D

1998 1999

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

2000

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

2001

J F M A M J J A S

AVERAGE DISCHARGE, IN CUBIC FEET PER SECOND

CONCENTRATION, IN MILLIGRAMS PER LITER

Discharge

Nitrogen

Phosphorus

0.001

0.004

0.01

0.04

0.1

0.4

1

4

10

40

100

300

Water Year 1999 Water Year 2000 Water Year 2001

Figure 8.  Total nitrogen (ammonia plus organic nitrogen) and total phosphorus in water from Chester 

Creek at Arctic Boulevard, water years 1999-2001.
for moderate-contact recreational waters for E. coli and 

enterococci bacteria are 298 and 78 organisms per 100 milliliters (col/100 mL), respectively, based on the geometric 

mean of generally not less than 5 samples equally spaced 

during a 30-day period (USEPA, 1986a). The Alaska 

State standard for fecal coliform bacteria in water used for 

recreation is 100 col/100 mL (Alaska Department of Environmental Conservation, 2003) and is intended to apply to 

the geometric mean of concentrations in samples collected 

during a period of no more than 30 days. Concentrations 

of bacteria in Chester Creek at the Arctic Boulevard site 

(table 2) generally exceeded guidelines for recreational 

use. Potential sources of fecal bacteria may include wastes 

from onsite septic systems, leaking sewer lines, domestic 

animals, waterfowl, and other wildlife.

Only a few fecal-indicator bacteria samples were 

analyzed from the Tank Trail and Boniface Parkway sites. 

All concentrations at the Tank Trail site were lower than 

recreational-use guidelines. Concentrations at the Boniface

Parkway site were higher than at the Tank Trail site, but 

varied widely.

Organic Constituents

All samples analyzed contained low concentrations 

of at least one organic compound (table 3). Most of the 

detected compounds were at concentrations less than the 

method-detection limit for the analytical procedure used. 

All organic compounds detected in water samples were at 

concentrations less than USEPA drinking-water standards 

or guidelines.

Pesticides

Nine different pesticide compounds were detected in 

water from Chester Creek at Arctic Boulevard. Carbaryl, 

prometon, diazinon, and 2,4-D were the most frequently 

detected pesticides. Carbaryl, a broad-spectrum insecticide 

that is widely used throughout the Anchorage area to control spruce bark beetles, was detected in 75 percent of the 

samples. Prometon, a nonselective herbicide commonly 

used to control broadleaf weeds and grasses around homes 

and along rights-of-ways, was detected in 70 percent of the

samples. Diazinon and 2,4-D were detected in 25 and 40 

percent of the samples, respectively. Most concentrations 

were estimated to be less than 0.05 μg/L, a value often 

used as the common minimum reporting level for pesticides. Carbaryl exceeded the 0.2 μg/L Canadian guideline 

for the protection of aquatic life (Canadian Council of 

Ministers of the Environment, 2002b) in 15 percent of 

the samples, the greatest concentration was 0.33 μg/L. 

All carbaryl concentrations were substantially less than 

the USEPA guideline for drinking water of 700 μg/L. No 

other pesticide exceeded applicable aquatic-life guidelines. 

The occurrence of pesticides in Chester Creek is consistent with what has been found in other urban streams 

hroughout the nation by the NAWQA program, where the 

nsecticides diazinon, carbaryl, chlorpyrifos, and malahion, and the herbicides atrazine, simazine, and prometon, 

ere frequently detected in urban streams (U.S. Geologial Survey, 1999). 

Low concentrations of hexachlorobenzene, used in 

aking other organic chemicals including wood preservaives, and pentachloroanisole, a degradation product of the 

ood preservative/fungicide pentachlorophenol banned 

n 1987, were detected in water using lipid-containing 

PMDs.

olatile Organic Compounds

All water samples collected from the Arctic Bouleard site contained a mixture of VOCs, including compoents of petroleum products and the probable by-products 

f chlorinated disinfection of public-water supplies. Yet, 

ost concentrations of detected VOCs were quite low, 

elow 1 μg/L. Only methylbenzene (also known as tolune) and methyl tert-butyl ether (MTBE) were detected at 

oncentrations exceeding 0.2 μg/L—these compounds are 

ssociated with gasoline. No VOC concentration exceeded 

pplicable drinking-water standards or guidelines or 

quatic-life guidelines. However, not all of the detected 

OCs in surface water have a federally established drinkng-water standard or guideline.

Toluene and trichloromethane (chloroform) were 

resent in every water sample from Chester Creek that 

as analyzed for VOCs. Concentrations of toluene were 

s great as 0.22 μg/L in high streamflows after rains, most 

ikely from surface runoff from roads and parking areas. 

oncentrations of MTBE, a gasoline additive that was 

sed in Anchorage during the 1992-93 winter, were as 

reat as 0.8 μg/L in Chester Creek during winter low-flow 

onditions during 1999, most likely from ground-water 

ischarge. MTBE concentrations became diluted and 

ecreased as rain and snowmelt runoff increased. A likely 

ource of the frequent occurrence of chloroform in Cheser Creek is surface runoff and ground-water discharge 

erived from chlorinated public-supply water. Chloroform 

s typically formed in drinking water during and after 

hlorination when naturally occurring organic substances 

n water react with chlorine.

emivolatile Organic Compounds

SVOCs include many compounds associated with 

ndustrial activities and processes, such as phthlates used 

n plastics, phenols used in disinfectants and in manufacuring chemicals. SVOCs also include polycyclic aromatic 

ydrocarbons (PAHs) (Lopes and Furlong, 2001) which 

re a large group of compounds comprised of fused benene rings and are a result of a mix of anthropogenic and 

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Water-Quality Characteristics 1
1 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

Table 3.  Summary of organic compounds detected in water sampled from Chester Creek at Arctic Boulevard, 1998-2001.

[--, no data, standard, or guideline; E, estimated value; USEPA, U.S. Environmental Protection Agency; MCL, maximum contaminant level; HAL, 

Lifetime health advisory level]

Constituent

Number of 

samples 

analyzed

Number of 

detections

Concentration, in micrograms per liter

Predominant 

Method-detec use -

tion limit

Maximum 

concentration

USEPA drinking-water 

standard or 

guideline1

Canadian 

guideline 

for freshwater 

aquatic 

life, 

Probable 

effect 

level2

Pesticides

Carbaryl 20 15 0.003 E0.33 700 (HAL) 0.2 Insecticide

Prometon 20 14 0.018 0.073 100 (HAL) -- Herbicide

2,4-D 20 8 0.08-0.15 0.41 70 (MCL, HAL) -- Herbicide

Diazinon 20 5 0.002-0.04 0.043 0.6 (HAL) -- Insecticide

Dichlorprop 20 2 0.03-0.05 0.13 -- -- Herbicide

p,p’-DDE 20 2 0.006 E0.002 -- -- Degredation

 product of the

 insecticide

 DDT

2,4-D methyl ester 12 1 0.086 E0.024 -- -- Herbicide

Bendiocarb 12 1 0.06 E0.020 -- -- Insecticide

Clopyralid 20 1 0.04-0.23 E0.06 -- -- Herbicide

Hexachlorobenzene <3> 1 1 -- Detected 1 (MCL) -- Wood preservative

Pentachloroanisole <3> 1 1 -- Detected -- -- Wood preser

vative and

fungicide 

Volatile organic compounds

Chloroform (trichloromethane) 11 11 0.024 0.18 100 (MCL) 1.8 Solvent and

 by-product of

 chlorination

Toluene (methylbenzene) 11 11 -- 0.23 1,000 (MCL) 2.0 Gasoline

 aromatic

 hydrocarbon

Benzene 11 10 0.1 E0.08 5 (MCL) 370 Gasoline

 aromatic

 hydrocarbon

Tetrachloroethylene (PCE) 11 9 0.2 0.05 5 (MCL) 111 Solvent

Methyl tert-butyl ether (MTBE) 11 6 0.3 0.8 20-40 (HAL) -- Gasoline 

oxygenate

Ethylbenzene 11 5 0.06 E0.03 700 (MCL) 90 Gasoline 

aromatic 

hydrocarbon

m- & p Xylene (1,3-dimethylbenzene and 1,4-dimethylbenzene)

11 5 0.12 E0.10 10,000 (MCL) -- Gasoline 

aromatic 

hydrocarbon
natural activities, primarily combustion of fossil fuels and 

wood. Some PAHs, phthalates, and phenols are probable 

human carcinogens and endocrine disruptors.

Analyses of extracts from SPMDs placed in Chester 

Creek at Arctic Boulevard indicate that few SVOCs were 

detectable in the water column. Total PAH concentration 

was estimated as 0.018 μg/L (Jim Petty, USGS Columbia 

Environmental Research Center, written commun., 2001). 

Three priority-pollutant PAH compounds (fluoranthene, 

pyrene, and chrysene) were detected. The estimated pyrene 

concentration of 0.0035 μg/L was within the range known 

to cause adverse effects on fingerling fishes (Jim Petty, 

USGS Columbia Environmental Research Center, written 

commun., 2001). Estimated concentrations of fluoranthene 

and pyrene in water were less than the Canadian environmental quality guidelines for the protection of aquatic 

life, 0.04 and 0.025 μg/L, respectively (Canadian Council 

of Ministers of the Environment, 2002b). No aquatic-life 

guideline exists for chrysene. 

Chemical Analyses of Streambed and Lakebed Sediments 1

Table 3.  Summary of organic compounds detected in water sampled from Chester Creek at Arctic Boulevard, 1998-2001.—

Continued

[--, no data, standard, or guideline; E, estimated value; USEPA, U.S. Environmental Protection Agency; MCL, maximum contaminant level; HAL, 

Lifetime health advisory level]

Constituent

Number of 

samples 

analyzed

Number 

of detections

Concentration, in micrograms per liter

Method- Predominant use

detection 

limit

Maximum 

concentration

USEPA drinking-water 

standard or 

guideline1

Canadian 

guideline for 

freshwater 

aquatic 

life, 

Probable 

effect 

level2

Volatile organic compounds

Ortho-Xylene (1,2-dimethylbenzene)

11 4 0.12 E0.05 10,000 (MCL) -- Gasoline aromatic 

hydrocarbon

1,2,4-Trimethylbenzene 11 3 0.11 E0.06 -- -- Organic synthesis

cis-1,2-dichloroethene 11 3 0.04 E0.05 70 (MCL) -- Solvent

Methylene chloride (dichloromethane)11 3 0.8 E0.1 5 (MCL) 98.1 Solvent

Dichlorodifluoromethane (CFC12)11 2 0.3 E0.1 1,000 (HAL) -- Refrigerant

Isopropylbenzene (1-Methylethyl 

benzene)

11 1 0.06 E0.01 -- -- Organic synthesis

n-propylbenzene 11 1 0.08 E0.01 -- -- Solvent

Bromodichloromethane 11 1 0.05 E0.02 1,000 (HAL) -- Organic synthesis

Methylchloride (Chloromethane) 11 1 0.5 E0.1 3 (HAL) -- Refrigerant

Trichloroethylene (TCE) 11 1 0.08 E0.01 5 (MCL) 21 Solvent

Trichlorofluoromethane (CFC-11) 11 1 0.18 E0.07 2,000 (HAL) -- Refrigerant

Semivolatile organic compounds - polycyclic aromatic hydrocarbons 

Chrysene3 1 1 -- E0.0008 -- -- Found in fossil 

fuels, tar, and 

asphalt, and 

occurs as a 

by-product of 

the incomplete 

combustion of 

wood or gasoline

Fluoranthene3 1 1 -- E0.0012 -- 0.04

Pyrene3 1 1 -- E0.0035 -- 0.025

1

U.S. Environmental Protection Agency (2002).

2

Canadian Council of Ministers of the Environment (2002b).

3

Concentrations of these organic compounds were determined using extracts from semipermeable membrane sampling devices that were in the 

stream from May 18 to July 13, 2000.
18 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

Chemical Analyses of Streambed 

and Lakebed Sediments

Trace elements and some organic compounds occur 

naturally in the environment, but also may be redistributed 

and concentrated by human activities. They are unevenly 

distributed in the aquatic environment and, by the process 

of adsorption, some tend to be associated with fine-grained 

sediment particles (Horowitz and Elrick, 1988). Bedsediment samples can be used to provide time-integrated 

records of contaminant concentrations. 

Trace Elements

Elevated concentrations of some trace elements—

such as arsenic, cadmium, chromium, copper, lead, 

mercury, nickel, selenium, and zinc—can be toxic to 

aquatic organisms. The slow elimination rate of some trace 

elements from many aquatic organisms can lead to bioaccumulation and biomagnification in aquatic food chains. 

Table 4 summarizes the concentrations of selected trace 

elements found in streambed sediments in Chester Creek, 

in Cook Inlet Basin streams, and in streams throughout 

the nation that were sampled by the NAWQA program. 

Arsenic, chromium, copper, mercury, nickel, and selenium 

appear to be at somewhat higher concentrations in sediments from Chester Creek relative to median concentrations from streambed sediments collected throughout the 

nation. Concentrations of cadmium, copper, lead, and zinc 

increased in the downstream direction in Chester Creek; 

these increases in concentrations greater than the level 

present at the upstream site are most likely from urban 

rather than geologic sources. Concentrations of selenium 

in streambed sediments decreased in the downstream 

direction. Arsenic, chromium, lead, and zinc in some sediment samples from Chester Creek exceeded the PEL based 

on bulk sediments and may adversely affect aquatic organisms. One chromium concentration of 200 μg/g from a 

streambed sample collected at the most upstream site may 

be anomalous and does not compare well to a concentration of 81 μg/g collected at the same site (table 4).

Cores of lakebed sediments from Westchester Lagoon 

and Hillstrand Pond were collected during June 1998 and 

individual layers were analyzed to determine how concentrations of trace elements have changed with time. One 

particular element of interest whose history was reconstructed was lead, which is toxic to humans and animals. 

Natural and anthropogenic sources contribute lead to 

the environment, but lead from anthropogenic sources, 

mainly from atmospheric emissions, is many times the 

total contribution from natural sources. Lead concentrations in the lakebed sediment cores (fig. 9) followed a 

trend similar to that shown in other urban lakes sampled in 

the NAWQA program throughout the nation. Specifically, 

lead concentrations increased in urban reservoir and lake 

sediments from the 1960s through the early 1970s, peaked 

in the mid 1970s, and then decreased with the introduction 

of unleaded gasoline (Callender and Van Metre, 1997). 

The use of lead in other products, such as paints, ceramics, caulk, and pipe solder, has also been reduced greatly 

in recent years. Concentrations of lead in the sediment 

cores from Hillstrand Pond and Westchester Lagoon have 

decreased by 73 and 84 percent, respectively, from their 

peak levels yet remain near or greater than the PEL of 91.3 

μg/g (fig. 9). Lead concentrations in recently deposited 

lakebed sediments are nearly 10 times greater than predevelopment levels and levels in streambed sediments above 

urban development. Large amounts of lead remain in local 

urban soils and aquatic sediments, and it may take years or 

even decades to reduce these concentrations to background 

levels, even if there are no new sources of lead pollution.

In contrast to the trend in lead concentrations, 

concentrations of zinc (fig. 10) and cadmium in lakebed 

sediments increased during the 1970s and remained at 

elevated levels during the 1980s and 1990s. Zinc concentrations in sediments from Westchester Lagoon ranged 

from 129 μg/g in the deepest sample to 690 μg/g in the 

shallowest sample, with a peak concentration of 921 μg/g 

in sediments deposited around 1993. Cadmium concentrations in sediments from Westchester Lagoon ranged from 

0.2 μg/g in sediments deposited around 1971 to 1.7 μg/g 

in most recently deposited sediments. Canadian guidelines 

for the protection of aquatic life for zinc and cadmium 

are 315 and 3.5 μg/g, respectively (Canadian Council of 

Ministers of the Environment, 2002b). Zinc concentrations 

have exceeded this PEL in sediments from Hillstrand Pond 

and Westchester Lagoon since the mid-1970s (fig. 10). 

Zinc is an additive to rubber in automobile tires and is used 

as a protective plating on metals. Elevated zinc concentrations relative to levels at the upstream site may be associated with automobile use (tire wear) or from the contact of 

water with galvanized metal products. Cadmium is used 

for electroplating and for pigments used in paint, printing 

ink, and plastics (Hem, 1985). It also is used extensively as 

a stabilizer for PVC plastic and in electrical batteries and 

fluorescent and video tubes.

Methylmercury is produced from inorganic mercury 

by methylation, a microbial process that is controlled by 

certain bacteria and enhanced by chemical and environmental variables, such as the presence of organic matter 

and oxygen. Methylmercury is readily bioaccumulated 

and biomagnified. It is also the primary form of mercury 

in fish and is a potent neurotoxin to humans and wildlife 

(fish, birds, and mammals). The concentration of total 

mercury in a bulk sample from the Arctic Boulevard site 

(0.109 μg/g) was lower than concentrations in sieved 

samples from the same site (0.17–0.18 μg/g). The concentration of methylmercury in the bulk sediment sample was 

0.00038 μg/g, indicating that small amounts of mercury 

may be methylating. Mercury concentrations in sieved 
Chemical Analyses of Streambed and Lakebed Sediments 19

Table 4.  Concentrations of selected trace elements and organic compounds in streambed and lakebed sediments from the

Chester Creek watershed, 1998-2001.

[Concentrations of trace elements in streambed sediments are in micrograms per gram, dry weight, using particles finer than 0.063 millimeter in 

diameter; concentrations of trace elements in lakebed sediments are in micrograms per gram, dry weight, using bulk samples; concentrations of organic 

carbon are in percent; Concentrations of organic compounds in streambed sediments are in micrograms per kilogram, dry weight, using particles finer 

than 2 millimeters in diameter; Concentrations of organic compounds in lakebed sediments are in micrograms per kilogram, dry weight, using bulk 

samples; <, less than; E, estimated; --, not determined or no guideline]

Concentration

Streambed sediment Lakebed sediment

Constituent

South 

Branch of 

South Fork 

Chester 

Creek at 

Tank Trail

South 

Branch 

of South 

Fork 

Chester 

Creek at 

Boniface 

Parkway

Chester 

Creek at 

Arctic 

Boulevard

Range of 

concentrations 

in streambed 

sediments in 

the Cook Inlet 

Basin

National 

median 

concentration from 

NAWQA 

streambedsediment 

sites1

Hillstrand 

Pond 

below 

Lake Otis 

Parkway

Westchester Lagoon 

above 

Minnesota 

Drive

Canadian 

guideline 

for the 

protection 

of aquatic 

life, Probable effect 

level2

Trace elements 2 samples 1 sample 2 samples 49 samples 

from 47 sites

10 

samples

 20 

samples

Arsenic 15 - 17 15 23 - 26 1.7 - 88 7.7 15 - 18 5 - 7.7 17

Cadmium 0.2 0.7 1.0 - 1.2 <0.1 - 4.6 0.45 0.4 - 1.2 0.2 - 1.7 3.5

Chromium 81 - 200 110 120 3 - 220 63.5 94 - 110 86 - 103 90

Copper 38 - 42 53 60 - 64 3 - 92 28 52 - 63 51 - 72 197

Lead 10 - 12 61 90 - 110 <1 - 230 25.9 76 - 280 29 - 544 91.3

Mercury 0.16 0.17 0.17 - 0.18 0.03 - 0.81 0.073 0.20 - 0.27 0.14 - 0.31 0.49

Nickel 29 - 47 47 50 - 64 <2 - 130 29 50 - 60 40 - 55 --

Selenium 2.5 - 5.8 1.4 0.8 - 1.1 <0.1 - 5.8 0.7 0.9 - 1.9 -- --

Zinc 82 - 110 420 590 - 600 16 - 1,800 110 170 - 980 129 - 921 315

Organic carbon 2 samples 1 sample 2 samples 49 samples 

from 47 sites

10 

samples

 20 

samples

Organic carbon 7.1 - 16 6.9 6.0 - 7.0 0.05 - 16 2.5 6.5 - 10 1.9 - 8.5 --

Organic compounds

Methylmercury

 1 

sample 5 sites

Methylmercury3 -- -- 0.000 0.00001-0.0051 -- -- -- --

Polycyclic aromatic 

hydrocarbons (PAHs) 1 sample 1 sample 3 samples 49 samples from 47 sites

11 

samples 8 samples

Benz[a]anthracene <50 170 120-530 <50-530 -- 9-126 340-601 385

Benzo[a]pyrene <50 170 120-540 <50-540 -- 11-122 276-555 782

Benzo[ghi]perylene <50 E70 E60-E230 <50-230 -- 7-120 294-540 --

Benzo[k]fluoranthene <50 190 120-480 <50-480 -- 10-184 316-464 --

Chrysene <50 290 E150-670 <50-670 -- 19-306 785-1060 862

Fluoranthene <50 470 340-1200 <50-1200 -- 19-425 800-1740 2355

Indeno[1,2,3-cd]pyrene <50 E100 80-360 <50-360 -- 7-90 270-434 --

Naphthalene <50 <50 <50-E50 <50-78 -- 7-24 44-80 391

Phenanthrene <50 330 220-730 <50-730 -- 33-232 617-974 515

Pyrene <50 420 320-1100 <50-1100 -- 30-490 884-2100 875

2,6-Dimethylnaphthalene<50 60 50-E80 <50-80 -- -- -- --
20 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

Table . Concentrations of selected trace elements and organic compounds in streambed and lakebed sediments from the

Chester Creek watershed, 1998-2001.

[Concentrations of trace elements in streambed sediments are in micrograms per gram, dry weight, using particles finer than 0.063 millimeter in 

diameter; concentrations of trace elements in lakebed sediments are in micrograms per gram, dry weight, using bulk samples; concentrations of 

organic carbon are in percent; Concentrations of organic compounds in streambed sediments are in micrograms per kilogram, dry weight, using particles finer than 2 millimeters in diameter; Concentrations of organic compounds in lakebed sediments are in micrograms per kilogram, dry weight, 

using bulk samples; <, less than; E, estimated; --, not determined or no guideline]

Concentration

Streambed sediment Lakebed sediment

Constituent

Phthalates

South 

Branch 

of South 

Fork 

Chester 

Creek 

at Tank 

Trail

South 

Branch of 

South Fork 

Chester 

Creek at 

Boniface 

Parkway

Chester 

Creek at 

Arctic 

Boulevard

Range of concentrations 

in streambed 

sediments in 

the Cook Inlet 

Basin

National 

median 

concentration from 

NAWQA 

streambedsediment 

sites1

Hillstrand 

Pond 

below 

Lake Otis 

Parkway

Westchester Lagoon 

above 

Minnesota 

Drive

Canadian 

guideline 

for the 

protection 

of aquatic 

life, Probable effect 

level2

 1 sample 1 sample 

samples

29 samples 

from 2 sites

bis(2-Ethylhexyl) phthalate

E20 1500 1000-2400 <50-2400 -- -- -- --

Di-n-butyl phthalate <50 80 50-E140 <50-140 -- -- -- --

Di-n-octyl phthalate <50 <50 110-420 <50-420 -- -- -- --

Phenols 1 sample 1 sample 

samples

29 samples 

from 2 sites 11 samples 8 samples

p-Cresol 100 780 50-620 <50-1200 -- 32-531 110-2500 --

Phenol E30 130 E50-130 <50-130 -- 35-552 152-357 --

Organochlorine pesticides samples 

from  sites 11 samples 8 samples

p,p’-DDD -- -- -- <1 -- 1.2-24 1.8-25 8.51

p,p’-DDE -- -- -- <1 -- 1.3-13 3.3-14 6.75

p,p’-DDT -- -- -- <2 -- <1 <1-12 4.77

Polychlorinated 

biphenyls

 samples 

from  sites 10 samples 8 samples

Total polychlorinated -- biphenyls -- -- <50 -- 37-245 70-620 277

1

National median concentrations from Chalmers (2002)

2

Guidelines from Canadian Council of Ministers of the Environment (2003) using bulk samples 

3

Concentration of methylmercury is from a bulk sample

sediment samples from all three sites on Chester Creek 

were greater than the national median concentration from 

NAWQA sites (0.07 μg/g), but less than Canadian guidelines for the protection of aquatic organisms (0.49 μg/g).

Semivolatile Organic Compounds

Concentrations of SVOCs in streambed sediments 

generally increased in the downstream direction in Chester 

Creek. Lakebed sediments from Westchester Lagoon also 

contained higher concentrations of SVOCs than Hillstrand 

Pond or recently deposited streambed samples. No PAH 

compounds were detected in streambed sediments at the 

Tank Trail site, but several PAH compounds were detected 

at the streambed sediments at the Arctic Boulevard site and 

in lakebed sediments from Westchester Lagoon (table 4). 

Some of the streambed sediments from the Arctic Boulevard site and lakebed sediments from Westchester Lagoon 

had concentrations of three PAHs—benz(a)anthracene, 

phenanthrene, and pyrene—that exceeded Canadian sediment guidelines for protection of aquatic life.
Chemical Analyses of Streambed and Lakebed Sediments 21

DATE OF SEDIMENT DEPOSITION

Hillstrand Pond below 

Lake Otis Parkway

(lakebed core)

Westchester Lagoon above Minnesota Drive

(lakebed core)

South Branch of South Fork Chester Creek at Tank Trail

(streambed sediment sample)

South Branch of 

South Fork Chester Creek 

at Boniface Parkway

(streambed sediment

sample)

Chester Creek 

at Arctic Boulevard

(streambed sediment

sample)

Probable effect level, 91 micrograms per gram 

10

100

1000

5

6

7

8

20

30

40

50

60

70

80

200

300

400

500

600

700

800

LEAD CONCENTRATION, IN MICROGRAMS PER GRAM

1970 1975 1980 1985 1990 1995 2000

Figure 9.  Temporal trends in lead concentrations in streambed sediments and cores of 

lakebed sediments from the Chester Creek watershed, 1970-2000.

DATE OF SEDIMENT DEPOSITION

Hillstrand Pond below

Lake Otis Parkway

(lakebed core)

Westchester Lagoon above Minnesota Drive

(lakebed core)

South Branch of South Fork Chester Creek at Tank Trail

(streambed sediment sample)

South Branch of 

South Fork Chester Creek 

at Boniface Parkway

(streambed sediment

sample)

Chester Creek 

at Arctic Boulevard

(streambed sediment

sample)

1970 1975 1980 1985 1990 1995 2000

100

1000

50

60

70

80

90

200

300

400

500

600

700

800

900

ZINC CONCENTRATION, IN MICROGRAMS PER GRAM

Probable effect level, 315 micrograms per gram

Figure 10.  Temporal trends in zinc concentrations in streambed sediments and cores of 

lakebed sediments from the Chester Creek watershed, 1970-2000.
Organochlorine Pesticides and 

Polychlorinated Biphenyls

Even though the uses of organochlorine pesticides, 

such as chlordane, dieldrin, dichloro-diphenyl-trichloroethane (DDT), and polychlorinated biphenyls (PCBs) were 

banned in the United States in 1970s and 1980s because of 

human health and ecosystem concerns, they are extremely 

persistent in the environment and are still found in stream 

and lake sediments and in tissues of aquatic organisms 

throughout the nation. DDT and PCB compounds were 

detected in sediment cores from Hillstrand Pond and 

Westchester Lagoon. The summed concentration of DDT 

and its metabolites was as high as 51 μg/kg in lakebed 

sediments deposited during the mid-1970s in Westchester 

Lagoon, whereas the concentration in recently-deposited (around 1998) sediments was 8.1 μg/kg (fig. 11). In 

the 1970s, some individual concentrations of the DDT 

metabolites p,p’-DDD, p,p’-DDE, and p,p’-DDT in the 

lakebed sediments exceeded Canadian guidelines for 

protection of aquatic life (1.8, 6.3, and <2 μg/kg, respectively). Concentrations of DDT metabolites in recently 

deposited sediments did not exceed these guidelines. 

Concentrations of total PCBs in lakebed sediments from 

Westchester Lagoon deposited in the mid-1970s were as 

great as 620 μg/kg—the most recently deposited sediments 

had a concentration of 147 μg/kg (fig. 12). The Canadian 

guideline for protection of aquatic life is 277 μg/kg of total 

PCB (Canadian Council of Ministers of the Environment, 

2002b). 

Chemical Analyses of Fish Tissues

Like sediment, concentrations of contaminants in fish 

tissue can provide a time-integrated assessment of water 

quality and can help assess the potential ecological effects 

on aquatic organisms. Table 5 shows concentrations of 

selected trace elements and organic compounds in samples 

of whole slimy sculpin (Cottus cognatus) collected near 

the Arctic Boulevard site in 1998 and 1999.

Trace Elements

Concentrations of lead and zinc in sculpin collected 

from Chester Creek at Arctic Boulevard were among the 

highest in the Cook Inlet Basin (Frenzel, 2000). Arsenic, chromium, copper, selenium, and zinc in sculpin 

from Chester Creek and other Cook Inlet Basin streams 

had higher concentrations than were observed in sculpin 

samples from urban, forest, and reference sites in the 

Puget Sound NAWQA Study Unit in Washington (Frenzel, 

2000). Concentrations of mercury in whole sculpin from 

Chester Creek (0.07-0.11 μg/g) were lower than median 

value in sculpin from Puget Sound’s forest reference sites 

(0.14 μg/g) and less than levels of concern for potential 

oxicity. For comparison, the “action level” for methylmerury, the primary form of mercury in fish, established by 

he U.S. Food and Drug Administration (2001) is 1.0 μg/g 

or the edible portions of all fin fish, crustaceans, and 

ollusks. Of the trace elements analyzed, only selenium 

oncentrations appear to be at levels of potential concern. 

ypical selenium concentrations at background sites 

hroughout the United States are less than 2 μg/g (U.S. 

epartment of Interior, 1998), whereas selenium concenrations of 3.0 and 4.9 μg/g were observed in composite 

amples of whole slimy sculpin from Chester Creek. 

emly (1996) suggested that selenium concentrations 

reater than 4 μg/g in whole fish produce adverse health 

ffects in some fish species.

rganochlorine Pesticides and 

olychlorinated Biphenyls

No organochlorine pesticides were detected in whole 

limy sculpin at the 5 μg/kg level, however, the concentraion of total PCBs was 79 μg/kg. Slimy sculpin are not 

ommonly consumed by humans, but may be consumed 

y other fish and birds. Because a national standard for the 

rotection of fish-eating wildlife does not exist, a comparion was made to a guideline from the State of New York 

Newell and others, 1987). That guideline recommends 

hat for the protection of fish-eating wildlife, total PCB 

oncentrations in fish tissues do not exceed 110 μg/kg, wet 

eight.

cological Characteristics

The examination of number and types of aquatic 

rganisms present in a stream reach can be used to assess 

he physical, chemical, and biological qualities of that 

each because each of the numerous species has its own 

nvironmental requirements and tolerances. In general, the 

umber of distinct species, genera, or families of algae, 

quatic macroinvertebrates, and fish reflects the health 

f the community. Species richness generally increases 

ith increasing water quality, habitat stability, and habitat 

iversity. In Chester Creek, the composition of the algal 

nd invertebrate communities at the three water-monitorng sites indicates that the overall quality of the stream 

egrades in the downstream direction and as the amount of 

rbanization in the watershed increases.

hysical Environment

Aquatic biological communities are affected not only 

y water quality but also by its aquatic and riparian habitat. 

learing of forests, draining and filling of wetlands, and 

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D

t

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c

b

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s

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22 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001
Ecological Characteristices 2

1

10

100

2

3

4

5

6

7

8

20

30

40

50

60

70

80

TOTAL DDT, IN MICROGRAMS PER KILOGRAM

DATE OF SEDIMENT DEPOSITION

1970 1975 1980 1985 1990 1995 2000

Hillstrand Pond below Lake Otis Parkway

Westchester Lagoon above Minnesota Drive

Figure 11.  Temporal trends in total DDT concentrations in sediment cores from Westchester 

Lagoon and Hillstrand Pond, 1970-2000.

10

100

1000

20

30

40

50

60

70

80

200

300

400

500

600

700

800

TOTAL PCB, 

IN MICROGRAMS PER KILOGRAM

1970 1975 1980 1985 1990 1995 2000

Probable effect level, 277 micrograms per kilogram

DATE OF SEDIMENT DEPOSITION

Hillstrand Pond below Lake Otis Parkway

Westchester Lagoon above Minnesota Drive

Figure 12.  Temporal trends in total PCB concentrations in sediment cores from Westchester 

Lagoon and Hillstrand Pond, 1970-2000.
channelizing and constraining the stream for urban development can change a stream’s substrate, in-stream cover, 

channel morphology, and riparian conditions. The physical 

conditions at each of the water monitoring sites were documented so that future comparisons could be made.

Chester Creek upstream of the Tank Trail is an 

unmodified stream channel in a forested setting (fig. 13 

and table 6). The reach is the steepest of the Chester Creek 

sites and is dominated by riffle habitat. The streambed 

substrate is primarily composed of coarse gravel—finegrained sediments embed less than 10 percent of the 

streambed. The reach’s meandering channel pattern contributes to a relatively high abundance of undercut banks. 

The stream is mostly shaded by vegetation.

The Boniface Parkway reach is a low gradient, 

highly-modified straight channel upstream of Boniface 

Parkway. Multi-family housing units are present near the 

right (north) bank, and single-family homes occur near 

its left bank. The reach has culverts at both its upgradient 

and downgradient ends and mainly consists of run habitat. 

2 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

Table . Concentrations of selected trace elements and organic compounds in whole slimy sculpin collected from Chester

Creek at Arctic Boulevard and other streams and rivers in the Cook Inlet Basin, 1998-2001.

[Concentrations of trace elements in micrograms per gram, dry weight; Concentrations of organic compounds in micrograms per kilogram, wet weight; 

<, less than; --, not determined]

Concentration in whole slimy sculpin

Chester Creek at Arctic Boulevard Range of concentrations in fish tissue from 

other streams and rivers in the Cook Inlet Basin

Date sampled Date sampled

/1/1998 8/9/1999 //1998 - 8/8/2000

Trace elements 1 sites

Aluminum 350 260 39-267

Antimony <0.2 <0.2 Not detected

Arsenic 0.8 1.1 0.4-1.6

Barium 8.7 5.4 2.6-31

Beryllium <0.2 <0.2 Not detected

Boron 1.8 0.7 <0.2-1.9

Cadmium 0.3 <0.2 <0.2-0.4

Chromium 3 1.7 <0.5-3.6

Cobalt 0.5 0.4 <0.2-1.2

Copper 3.5 3.8 0.7-6.1

Iron 800 350 71-1000

Lead 1.3 0.8 <0.2-0.4

Manganese 50 52 5.4-230

Mercury 0.11 0.07 0.05-0.21

Molybdenum <0.2 <0.2 <0.2-0.3

Nickel 1.1 1.0 0.3-1.6

Selenium 3 4.9 1.4-10

Silver <0.2 <0.2 Not detected

Strontium 83 62 17-180

Uranium <0.2 <0.2 Not detected

Vanadium 2.5 1.4 0.5-2.5

Zinc 160 98 16-240

Organochlorine pesticides 10 sites

p,p’-DDE <5 -- <5 - 9.0

p,p’-DDT <5 -- <5 - 6.1

Polychlorinated biphenyls 10 sites

Total PCBs 79 -- Not detected
The streambed contains coarse and very-coarse gravels 

which are highly-embedded with fine-grained sediments. 

Although this section of the stream is the most shaded of 

the Chester Creek reaches, the banks are largely void of 

underbrush and are closely bordered by housing structures.

The Arctic Boulevard reach is upstream of the Arctic 

Boulevard crossing. A park is present near the reach’s right 

(north) bank, and single-family homes are near its left 

bank. The reach has a modified straight channel with relatively high and unstable banks. It contains runs and riffles 

and its streambed consists of highly-embedded fine-tomedium gravels. The reach is heavily shaded and residential lawns border the stream on much of its southern side.

Algae

The algal communities in the three reaches were 

examined during a summer low-flow period in 2000. Five 

algal phyla were identified. The diatom phyla had the 

greatest richness with greater than 30 species, varieties, 

or forms. The euglenoid, red, blue-green, and green algae 

phyla each had fewer than 10 species, varieties, or forms. 

In gravel riffles, blue-green algae was the most abundant 

algal division (having the greatest number of individuals) at the Tank Trail and Arctic Boulevard sites, whereas 

diatoms and red algae were the most abundant divisions at 

the Boniface Parkway site. In pools, the dominant division 

at the Tank Trail and Boniface sites was the diatom phyla, 

but blue-green algae was dominant at the Arctic Boulevard 

site.

The composition of algal communities changed as 

the stream flowed downstream and as the land contributing water to the stream became more urbanized. Although 

nutrient concentrations did not change appreciably, concentrations of sodium, magnesium, and chloride increase 

in the downstream direction. The relative abundance 

of algae that are tolerant of increased salinity, such as 

Diatoma moniliformis and Diatoma tenuis, increased from 

the headwaters to the mouth, as did specific conductance, 

an indicator of the amount of dissolved minerals in water 

(fig. 14).

Benthic Macroinvertebrates

Macroinvertebrates in this report refer to organisms 

such as insects, mollusks, and worms that spend some 

portion of their life cycle in streams on or within bottom 

sediments, debris, logs, macrophytes, or living or dead 

plant material. Many of these invertebrates live in or on 

streambed sediments where contaminants tend to concentrate; thus, the chance that the organisms may react to toxic 

substances is increased. Benthic invertebrates are sensitive 

indicators of many types of stream disturbances (Barbour and others, 1999). Ephemeroptera, Plecoptera, and 

Trichoptera are orders of insects considered to be relatively 

intolerant to environmental alteration, whereas, true flies 

(Diptera), such as midges, and worms can tolerate poor 

environmental conditions. Fairly even distribution among 

the four insect groups, with substantial representation of 

the three most sensitive groups, is indicative of good biotic 

conditions. Worms and midges tend to become increasingly dominant with decreasing habitat quality.

Macroinvertebrate samples were collected from five 

riffle locations and from all available habitats within each 

reach at each of the three sites along Chester Creek (Ourso,

2001; Ourso and Frenzel, 2003). Invertebrate-community 

structure appears to be affected by water quality, channelization, and accumulations of fine sediment (Ourso, 2001; 

Ourso and Frenzel, 2003). The relative compositions of the

five major macroinvertebrate groups in riffles at the Tank 

Trail site were fairly evenly distributed, but the non-insect 

group was overwhelmingly dominant at the Arctic Boulevard site (fig. 15). Worms made up most of the organisms 

present at the Arctic Boulevard site in the summer and fall 

samples. Midges made up about one-half of the organisms 

at the Boniface Parkway site during June 2000.

Fish

The composition of fish has changed in the Chester 

Creek watershed during the last 30 years. During the early 

1970s, coho salmon were the most common salmonid 

fish species, however, their population has been adversely 

affected by barriers to migration and degraded habitat 

and water quality, including sedimentation, channelization, bank damage, loss of riparian areas, storm-drain 

discharge, and residential and commercial runoff (Davis 

and Muhlberg, 2001). The dam and weir creating Westchester Lagoon is a partial barrier to returning anadromous 

fish and numerous culverts along the main stem and its 

tributaries limit the movements of juvenile and adult fish 

due to high water velocities. Although difficult, some 

adult coho salmon do make it to the upper reaches of the 

stream. A total of four species of fish were observed in the 

three reaches of Chester Creek during 1999-2000: rainbow 

trout (Oncorhynchus mykiss), slimy sculpin, Dolly Varden 

char (Salvelinus malma), and coho salmon (Oncorhynchus 

kisutch) (table 7). Threespine sticklebacks (Gasterosteus aculeatus) were observed downstream of the Arctic 

Boulevard reach, but none were observed in the three study

reaches. The proximity of the sticklebacks to the stream 

mouth is typical, as they often reside in estuaries or saltwater and spawn in freshwater. Sculpins were present in 

all three reaches during each sampling. Dolly Varden were 

abundant in the two upstream reaches but were absent at 

the downstream. Rainbow trout and coho salmon were 

present in all reaches, but not during each sampling. The 

abundance of rainbow trout is partially due to the stocking of this species by the Alaska Department of Fish and 

Game since 1971. Rainbow trout are not native to Chester 

Creek.

Ecological Characteristices 2
Summary and Conclusions

In 1998, the U.S. Geological Survey, as part of the 

National Water-Quality Assessment Program, began an 

assessment of water quality in the Cook Inlet Basin. One 

of the watersheds studied was Chester Creek, which drains 

shrub and forest covered uplands and urbanized lowlands 

in Anchorage, Alaska. Analyses of water, streambed 

and lakebed sediment, and aquatic organisms at multiple 

locations in the watershed found that the overall quality 

of the stream degraded in the downstream direction as the 

amount of urbanization in the watershed increased. 

Concentrations of calcium, magnesium, sodium, 

chloride, and sulfate in stream water increased in the 

downstream direction. Sodium chloride and magnesium 

chloride are used as road and sidewalk deicers. Nitrate 

2 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

Flow

0 25 50 Feet

EXPLANATION

Wetted channel

Riffle

Run

Pools Transects

Woody debris logs

Woody debris piles�

Boulders�

Bar�

A

B

Arctic Blvd

C

Boniface Par

kway

Lee Street

Tank Trail

0 25 50 Feet

Flow

0 25 50 Feet

Flow

Figure 1.  Reaches associated with the water-sampling sites: (a) South Branch of South Fork Chester Creek at Tank 

Trail, (b) South Branch of South Fork Chester Creek at Boniface Parkway, and (c) Chester Creek at Arctic Boulevard.
Summary and Conclusions 2

Table 6.  Physical characteristics for three reaches along Chester Creek.

Characteristic1

South Branch of 

South Fork Chester 

Creek at Tank Trail

South Branch of 

South Fork Chester 

Creek at Boniface 

Parkway

Chester Creek at 

Arctic Boulevard, 

Reach C

Date of measurement 7/13/2000 7/6/2000 5/9/2000

Reach and transect characteristics

Reach length (feet) 300 300 500

Reach sinuosity 1.47 1.01 1.03

Gradient (percent) 2.86 0.72 0.40

Riffle length (percent of reach) 54 27 34

Run length (percent of reach) 40 73 54

Pool length (percent of reach) 6 0 11

Frequency of pools with cover (number/bankfull width) 1.8 0.8 1.4

Frequency of wood (approximate pieces/bankfull width) 2.1 1.5 1.5

Channel morphology characteristics

Width (feet) 5.9 14.9 22.4

Ratio of bankfull width to depth 12.7 26.9 11.5

Bank Stability Index 8 9 11

Bank erosion abundance (percent) 77 0 45

Streambed characteristics

Silt (percent) 0 18 3

Sand (percent) 6 0 6

Fine-to-medium gravel (percent) 12 18 64

Coarse gravel (percent) 73 27 27

Very coarse gravel (percent) 9 27 0

Small cobble (percent) 0 6 0

Large cobble (percent) 0 0 0

Small boulder (percent) 0 3 0

Less than 1 percent embedded (percent of reach) 94 24 24

1-20 percent embedded (percent of reach) 0 21 12

Greater than 20 percent embedded (percent of reach) 6 55 64

Habitat characteristics

Overall habitat abundance (percent) 33 49 38

Woody debris abundance (percent) 2 20 22

Overhanging vegetation abundance (percent) 9 18 0

Boulder habitat abundance (percent) 0 11 0

Man-made habitat abundance (percent) 0 0 2

Undercut bank abundance (percent) 73 55 36

Riparian and related characteristics

Riparian closure (percent) 74 96 84

Shade (percent) 89 96 87

1

The definitions of these habitat characteristics and methods of measurement are described in Fitzpatrick and others, 1998
concentrations were low, generally about one-tenth of 

the drinking-water standard of 10 mg/L and did not 

change appreciably along the stream. About 25 percent 

of the water samples collected near the stream’s mouth 

contained total phosphorus exceeding 0.1 mg/L, the 

water-quality guideline for preventing nuisance plant 

growth in streams. High concentrations of phosphorus 

occurred when streamflows and suspended-sediment 

concentrations were greatest. Fecal-indicator bacteria 

concentrations at the intermediate (Boniface Parkway) and downstream urban (Arctic Boulevard) sites 

commonly exceeded Federal and State guidelines for 

water-contact recreation. Sources of fecal bacteria 

may include wastes from humans (domestic sewage), 

domestic animals, waterfowl, and other wildlife. 

One or more pesticides and volatile organic compounds were found in low concentrations in almost 

every stream sample collected at the Arctic Boulevard 

site, but their concentrations were generally less than 

1 μg/L and did not exceed applicable drinking-water 

standards or guidelines. The most frequently detected 

pesticides were carbaryl, prometon, 2,4-D, and diazinon. Concentrations of carbaryl exceeded a Canadian 

guideline for the protection of aquatic organisms in 

about 15 percent of the samples. Chloroform (a solvent and a by-product formed when chlorinated water 

reacts with organic matter) and toluene (a fuel-related 

product and by-product of petroleum combustion) 

were present in every water sample collected. Other 

fuel-related products, such as benzene, ethylbenzene, 

xylene, and MTBE, and the solvent tetrachloroethylene also were frequently detected. In general, the 

highest concentrations of inorganic and organic constituents were detected during runoff from snowmelt 

and rain at the downstream site, indicating that flushing 

of contaminants from urban land surfaces (such as roads, 

parking lots, and domestic yards) has a large influence on 

the water quality of Chester Creek.

Arsenic, chromium, copper, mercury, and nickel 

appear to be at naturally high concentrations in sediments 

from Chester Creek relative to streambed sediments collected throughout the nation, possibly due to local sources 

in the rocks. Runoff from urban activities increased concentrations of cadmium, copper, lead, and zinc in Chester 

Creek’s streambed and lakebed sediments relative to levels 

present at the site upstream of urban development. Arsenic, chromium, lead, and zinc in some sediment samples 

were at levels that can adversely affect aquatic organisms. 

Concentrations of lead in sediments from Hillstrand Pond 

and Westchester Lagoon have decreased since lead was 

removed from gasoline in the 1970s, but are still at levels 

exceeding background concentrations. Concentrations of 

three PAHs in sediments from the downstream site and 

from Westchester Lagoon exceeded Canadian guidelines 

for the protection of aquatic life. The source of these 

organic compounds may be from the burning of fossil fuels 

or wood. 

28 Water-Quality Conditions of Chester Creek, Anchorage, Alaska, 1998-2001

Upper Site Middle Site Lower Site

30

20

10

40

50

HALOPHILIC ALGAL TAXA, 

IN PERCENT RELATIVE BIOVOLUME

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER

0

180

120

60

240

300

0

Figure 1.  Relation of the proportion of algae that prefer 

water enriched with dissolved minerals (halophilic algae) to 

specific conductance.

0

20

40

60

80

100

RELATIVE PERCENTAGE OF DOMINANT 

MACROINVERTEBRATE GROUPS 

June

2000

South Branch 

of South Fork 

Chester Creek 

at Tank Trail

South Branch 

of South Fork 

Chester Creek at 

Boniface Parkway

Chester Creek at 

Arctic Boulevard

Sept.

1999

June

2000

Sept.

1999

June

2000

Sept.

1999

Ephemeroptera (mayflies)

Plecoptera (stoneflies)

Trichoptera (caddisflies)

Diptera (true flies)

Non insects (mostly worms)

EXPLANATION

Figure 1.  Dominant macroinvertebrate groups.
Table . Abundances of fish in three reaches of Chester Creek.

Reach Date Common name of fish 

species Abundance

South Branch of South Fork Chester Creek at Tank Trail June 21, 2000 slimy sculpin 4

coho salmon 2

rainbow trout 5

Dolly Varden 89

South Branch of South Fork Chester Creek at Boniface Parkway June 15, 2000 slimy sculpin 48

coho salmon 31

rainbow trout 29

Dolly Varden 91

Chester Creek at Arctic Boulevard September 9, 1999 slimy sculpin 23

October 19, 1999 slimy sculpin 40

rainbow trout 82

June 14, 2000 slimy sculpin 104

coho salmon 37

Selenium concentrations in some samples of whole 

slimy sculpin were at levels that may cause adverse 

effects; however, concentrations of selenium in streambed 

sediments in Chester Creek decreased in the downstream 

direction and appear to be naturally high relative to sites 

across the nation. Other trace elements, including lead 

and mercury, and selected organic compounds, including 

DDT and PCBs, were not present in tissues of whole slimy 

sculpin at levels of concern for fish-eating wildlife.

Communities of attached algae and benthic invertebrates showed impairment in the downstream direction as 

chemical concentrations and the amount of urbanization in 

the watershed increased. The relative abundance of algae 

that are tolerant of increased salinity increased from the 

headwaters to the mouth, as did the amount of dissolved 

minerals in water. The relative abundance of pollution-sensitive benthic invertebrate taxa decreased in the downstream direction, and the dominance of pollution-tolerant 

worms increased. 

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