Ground-Water Quality in the Cook Inlet Basin,

Alaska, 1999

By Roy L. Glass

U.S. GEOLOGICAL SURVEY

Anchorage, Alaska

2001

Prepared as part of the

National Water-Quality Assessment Program

Water-Resources Investigations Report 01–4208
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

Any use of trade, product, or firm names in this publication is for descriptive

purposes only and does not imply endorsement by the U.S. Government

For additional information Copies of this report can be

contact: purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey Information Services

4230 University Drive, Suite 201 Building 810

Anchorage, AK 99508–4664 Box 25286, Federal Center

Denver, CO 80225–0286

http://ak.water.usgs.gov
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-resources 

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 they represent 

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 waterquality 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, 

multiscale 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.

The NAWQA Program recognizes that a national 

assessment by a single program cannot address all waterresources 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, nongovernment 

organizations, industry, academia, and other stakeholder 

groups. The assistance and suggestions of all are greatly 

appreciated.

Robert M. Hirsch

Associate Director for Water

FOREWORD
CONTENTS V

CONTENTS

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

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

Purpose and Scope ..................................................................................................................................................... 2

Previous Investigations .............................................................................................................................................. 2

Acknowledgments...................................................................................................................................................... 5

Major Water-Quality Issues ................................................................................................................................................... 5

Environmental Setting and Hydrologic Conditions............................................................................................................... 6

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

Well Selection ............................................................................................................................................................ 7

Sample Collection ...................................................................................................................................................... 7

Sample Analyses ........................................................................................................................................................ 12

Quality Control........................................................................................................................................................... 13

Water-Quality Standards and Guidelines ................................................................................................................... 15

Physical Properties and Field Measurements ........................................................................................................................ 15

Major Ions.............................................................................................................................................................................. 16

Nutrients and Dissolved Organic Carbon .............................................................................................................................. 17

Trace Elements ...................................................................................................................................................................... 20

Pesticides ............................................................................................................................................................................... 21

Volatile Organic Compounds................................................................................................................................................. 23

Environmental Isotopes ........................................................................................................................................................ 25

Radioactive Isotopes .................................................................................................................................................. 25

Stable Isotopes of Hydrogen and Oxygen.................................................................................................................. 27

Age Dating of Ground-Water Recharge ................................................................................................................................ 28

Tritium........................................................................................................................................................................ 29

Chlorofluorocarbons .................................................................................................................................................. 30

Summary................................................................................................................................................................................ 32

References Cited.................................................................................................................................................................... 33

Appendixes ............................................................................................................................................................................ 37

APPENDIXES

1. Physical properties and field measurements for water sampled from wells in Cook Inlet Basin, 1999................ 39

2. Concentrations of major ions in water sampled from wells in Cook Inlet Basin, 1999 ........................................ 40

3. Concentrations of nutrients and dissolved organic carbon in water sampled from wells in Cook Inlet Basin,

1999........................................................................................................................................................................ 41

4. Concentrations of trace elements in water sampled from wells in Cook Inlet Basin, 1999 .................................. 42

5. Concentrations of pesticides in water sampled from wells in Cook Inlet Basin, 1999.......................................... 43

6. Concentrations of volatile organic compounds in water sampled from wells in Cook Inlet Basin, 1999............. 49

7. Activities of radioisotopes in water sampled from wells in Cook Inlet Basin, 1999............................................. 55

8. Environmental isotopes of hydrogen and oxygen in water sampled from wells in Cook Inlet Basin, 1999 ......... 56

9. Tritium analyses of water sampled from wells in Cook Inlet Basin, 1999 ............................................................ 57

10. Chlorofluorocarbon analyses of water sampled from wells in Cook Inlet Basin, 1999 ........................................ 58
VI Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

CONVERSION FACTORS and VERTICAL DATUM

Multiply by To obtain

inch (in.) 25.4 millimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

square mile (mi2) 2.590 square kilometer

gallon per minute (gal/min) 0.06309 liter per second

million gallons per day (Mgal/d) 0.04381 cubic meter per second

tritium unit (TU) 0.118 Becquerel per liter

picocurie per liter (pCi/L) 0.037 Becquerel per liter

In this report, temperature is reported in degrees Celsius (°C), which can be converted to degrees Fahrenheit (°F) by the equation

°F = 1.8 °C + 32

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929, formerly called “Sea-Level 

Datum of 1929”), which is derived from a general adjustment of the first-order leveling networks of the United States and Canada.

FIGURES

1. Map showing location and major geographic features of Cook Inlet Basin, Alaska............................................. 3

2. Map showing locations of ground-water sampling sites in Cook Inlet Basin, 1999 ............................................. 4

3. Diagrams showing major-ion composition of water sampled from wells in Cook Inlet Basin, 1999 ................... 18

4. Graph showing isotope ratios of deuterium and oxygen-18 for water sampled from wells in Cook Inlet

Basin, 1999............................................................................................................................................................. 29

5. Graph showing dates of recharge determined by using chlorofluorocarbon and tritium analyses of water

from wells in Cook Inlet Basin, 1999 .................................................................................................................... 31

TABLES

1. Identification, location, and characteristics of sampled wells in Cook Inlet Basin, 1999 ..................................... 8

2. Methods used to analyze water from wells in Cook Inlet Basin, 1999.................................................................. 12

3. Constituents detected in quality-control samples from Cook Inlet Basin, 1999.................................................... 13

4. Constituents that have relative-percentage differences greater than 10 percent in replicate samples from

Cook Inlet Basin, 1999........................................................................................................................................... 14

5. Statistical summary of physical properties and field measurements for water sampled from wells in Cook

Inlet Basin, 1999 .................................................................................................................................................... 15

6. Statistical summary of major-ion concentrations in water sampled from wells in Cook Inlet Basin, 1999.......... 16

7. Statistical summary of nutrient and dissolved organic carbon concentrations in water sampled from wells in

Cook Inlet Basin, 1999........................................................................................................................................... 19

8. Statistical summary of trace-element concentrations in water sampled from wells in Cook Inlet Basin, 1999.... 22

9. Pesticides detected in water sampled from wells in Cook Inlet Basin, 1999......................................................... 24

10. Volatile organic compounds detected in water sampled from wells in Cook Inlet Basin, 1999............................ 25

11. Statistical summary of radioisotopes, environmental isotopes, and chlorofluorocarbon concentrations in

water sampled from wells in Cook Inlet Basin, 1999 ............................................................................................ 26
WATER-QUALITY ABBREVIATIONS VII

WATER-QUALITY ABBREVIATIONS

Chemical concentrations and water temperature are given in metric units. Chemical concentration is given in milligrams 

per liter (mg/L), micrograms per liter (μg/L), or picograms per kilogram of water (pg/kg). Milligrams per liter is a unit 

expressing the concentration of chemical constituents in solution as weight (milligrams) of solute per unit volume (liter) of 

water. One milligram per liter is approximately equivalent to one part per million, one microgram per liter is approximately 

equivalent to one part per billion, and one picogram per kilogram is approximately equivalent to one part per quadrillion. 

Specific conductance is reported in microsiemens per centimeter at 25 degrees Celsius (μs/cm). Radioactivity is expressed in 

picocuries per liter (pCi/L) or tritium units (TU).

Stable isotope ratios are expressed as a departure of the ratio of two isotopes of an element in a given sample from the same 

ratio in an established standard; values are given in per mil (parts per thousand). Symbols and standards used to describe 

isotopes or their ratios are:

δD deuterium/hydrogen ratio, referenced to Vienna Standard Mean Ocean Water

δ18O oxygen-18/oxygen-16 ratio, referenced to Vienna Standard Mean Ocean Water

Unit abbreviations and related terms used in this report:

as N quantified as measured nitrogen

as P quantified as measured phosphorus

Mgal/d million gallons per day

mg/L milligram per liter

pCi/L picocurie per liter

g/kg gram per kilogram

pg/kg picogram per kilogram

μg/g microgram per gram, dry weight

μg/L microgram per liter

μm micrometer

μS/cm microsiemen per centimeter at 25°C

Acronyms used in this report:

CFC chlorofluorocarbon

DOC dissolved organic carbon

MCL maximum contaminant level, a health-based water-quality standard set by U.S. Environmental

Protection Agency

NAWQA National Water-Quality Assessment

NWQL National Water Quality Laboratory

PMCL proposed maximum contaminant level

SMCL secondary maximum contaminant level, an unenforceable guideline regarding taste, odor, color, and

certain other nonaesthetic effects of drinking water set by U.S. Environmental Protection Agency

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

VOC volatile organic compound

VSMOW Vienna Standard Mean Ocean Water
Abstract 1

Abstract

As part of the U.S. Geological Survey’s 

National Water-Quality Assessment Program, 

ground-water samples were collected from 34 

existing wells in the Cook Inlet Basin in southcentral Alaska during 1999. All ground-water 

samples were from aquifers composed of glacial 

or alluvial sediments. The water samples were 

used to determine the occurrence and distribution 

of selected major ions, nutrients, trace elements, 

volatile organic compounds, pesticides, radioisotopes, and environmental isotopes. Of 34 samples, 

29 were from wells chosen by using a grid-based 

random-selection process. Water samples from 

five major public-supply wells also were collected.

Radon-222 and arsenic concentrations 

exceeded drinking-water standards proposed by 

the U.S. Environmental Protection Agency in 39 

and 18 percent of sampled wells, respectively. The 

highest radon concentration measured during this 

study was 610 picocuries per liter; 12 of 31 samples exceeded the proposed maximum contaminant level of 300 picocuries per liter. The highest 

arsenic concentration was 29 micrograms per liter; 

6 of 34 samples exceeded the proposed maximum 

contaminant level of 10 micrograms per liter. 

Human activities may be increasing the concentration of nitrate in ground water, but nitrate concentrations in all samples were less than the maximum contaminant level of 10 milligrams per liter 

as nitrogen. Concentrations of nitrate were highest

in Anchorage and were as great as 4.8 milligrams 

per liter as nitrogen. Dissolved-solids concentrations ranged from 77 to 986 milligrams per liter; 

only 2 of 34 wells yielded water having greater 

than 500 milligrams per liter. Iron and manganese 

concentrations exceeded secondary maximum 

contaminant levels in 18 and 42 percent of samples, respectively.

Concentrations of all pesticides and volatile 

organic compounds detected in ground-water samples were very low, less than 1 microgram per liter. 

No pesticide or volatile organic compounds were 

detected at concentrations exceeding drinkingwater standards or guidelines. Water samples from 

one-half of the wells sampled had no detectable 

concentrations of pesticides or volatile organic 

carbons, at the parts-per-billion level.

Concentrations of stable isotopes of hydrogen 

and oxygen in ground-water samples were similar 

to concentrations expected for modern precipitation and for water that has been affected by evaporation. Tritium activities and concentrations of 

chlorofluorocarbons indicated that the water samples collected from most wells were recharged less 

than 50 years ago.

Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

By Roy L. Glass
2 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

INTRODUCTION

In 1991, the U.S. Geological Survey (USGS) 

began a full-scale implementation of the National 

Water-Quality Assessment (NAWQA) Program to provide a consistent description of the Nation’s groundand surface-water resources. The long-term goals of 

the program are to (1) determine the general groundand surface-water quality of the Nation’s water 

resources; (2) define long-term trends (or lack of 

trends) in water quality; and (3) identify, describe, and 

explain, to the extent possible, the major natural and 

human factors that affect measured water-quality conditions and trends (Gilliom and others, 1995). In meeting these goals, the program provides nationally 

consistent information useful to policy makers, managers, and scientists concerned with the Nation’s water 

resources.

NAWQA study-unit investigations of parts of 

most major river basins and aquifer systems throughout the Nation are the building blocks of the national 

assessment. More than 50 hydrologic systems have 

been studied; 20 investigations were started in 1991, 

16 more in 1994, and 15 more in 1997. The Cook Inlet 

Basin (COOK) study-unit investigation in south-central Alaska (fig. 1) began in 1997.

Purpose and Scope

One component of NAWQA ground-water studies focuses on water-quality conditions in major aquifers, primarily by aquifer-wide surveys (termed “subunit surveys”). The COOK “subunit” consisted of 

unconsolidated-deposits aquifers comprising mostly 

glacial and alluvial materials. These aquifers are the 

most important sources of present or future domestic, 

municipal, commercial, and industrial ground-water 

supplies in the Cook Inlet Basin. The geographic 

extent of the ground-water study was limited to developed areas within the Municipality of Anchorage and 

the Kenai Peninsula and Matanuska–Susitna Boroughs 

(fig. 2). The subunit survey consisted of sampling 29 

randomly selected wells within the study area that 

obtained water from unconsolidated-deposits aquifers.

Water samples also were collected from five of the 

most productive public-supply wells within the study 

area. Water samples from each of these 34 wells were 

collected once during 1999. Samples were analyzed to 

determine the occurrence and spatial distribution of 

selected physical properties, major ions, nutrients, dissolved organic carbon (DOC), trace elements, pesticides, volatile organic compounds (VOCs), and radioisotopes. Isotopes of oxygen and hydrogen, and concentrations of chlorofluorocarbons (CFCs) also were 

analyzed to help characterize the water and to help 

estimate the time that had elapsed since the water was 

recharged. This report includes discussions of the 

major water-quality issues in the COOK study unit; 

descriptions of the environmental setting and hydrologic conditions affecting ground-water quality and

of the methods of investigation; and statistical and 

graphic presentations of the data. Ground-water quality in the COOK study unit is compared to drinkingwater regulations and guidelines established by the 

U.S. Environmental Protection Agency (USEPA) and 

to ground water in other NAWQA study units.

Previous Investigations

Frenzel (1997) described the surface-water, 

ground-water, and biological studies being conducted 

within the COOK study unit under the NAWQA Program. Brabets and others (1999) described the environmental setting, including the physical, hydrologic, 

and aquatic biological characteristics of the aquifers 

and the major streams and rivers that flow into Cook 

Inlet and how these characteristics affect surface- and 

ground-water quality. Glass (1999) did a preliminary 

assessment of the quality of surface and ground water 

in the study unit through 1997, including statistical 

and graphical summaries of selected chemical constituents from about 550 wells and 31 sites on streams.

Figure 1. Location and major geographic features 

of Cook Inlet Basin, Alaska. Boundary of Cook Inlet 

aquifer system from Miller and others (1999).
INTRODUCTION 3

Mount Spurr

Redoubt

Volcano 

Iliamna 

Volcano

Augustine ▲Volcano

▲

▲

▲

▲

ALASKA RANGE

K E N A I M O U N T A I N S

CHUGACH MOUNTAINS

TALKEETNA

MOUNTAINS

•Mount 

McKinley

Sutton

Wasilla Palmer

Anchorage

Tyonek

Kenai

Soldotna

75 100 MILES

100 KILOMETERS

50

75

25

25 50

0

0

149o

60o

60o

154o

63o

152o

146o

63o

Cook Inlet Basin

study unit

ALASKA

Boundary of National Park

Boundary of Kenai National Wildlife Refuge

EXPLANATION

K E N A I P E N I N S U L A

Swanson River

Boundary of Chugach National Forest

Kenai 

National 

 Wildlife 

Refuge

Chugach 

National 

Forest

Kenai 

Fjords 

National 

Park

Katmai National Park

and Preserve

Lake Clark National Park

and Preserve

Denali National Park

and Preserve

Willow

Homer Cook Inlet aquifer system

Boundary of Cook Inlet Basin study unit

Volcano

Glacier

Nikiski

Road

Area of figure 2

Kenai River

Susitna River

Kasilof

 River

Knik River

Matanuska River

Talkeetna River

Susitna River

Chulitna River

Deshka River

Yentna River

Skwentna River

Beluga River

Chakachatna 

River

Drift River

Johnson

 River

Kamishak

 River

COOK INLET

Susitna River
4 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Figure 2. Locations of ground-water sampling sites, Cook Inlet Basin, 1999.

Glacier

EXPLANATION

Ground-water study area

Subunit survey

Public-supply survey

5

35

Matanuska−Susitna Borough

Kenai Peninsula Borough

Municipality

of Anchorage

COOK INLET

17

29

18

16

6 15

14

7 8

19

25

27

28

30

31 26

24

23

20

21

32

33

13 34

12

22

5

35

4

3 9 10

11

2

1

Borough boundary

Study Unit boundary

Sample sites and wells−Numbers are well numbers

0

0

10

10

20 MILES

20 KILOMETERS

▲

▲

▲

▲

▲

▲

151o 150o 149o

61o

15'

61o

61o

45'

30'
MAJOR WATER-QUALITY ISSUES 5

Most waters in streams and wells have small concentrations of major inorganic constituents, nutrients, 

trace elements, and organic compounds. However, 

suspended-sediment concentrations in glacier-fed 

streams are naturally high, and several streams and 

lakes in urban areas have high concentrations of fecalcoliform-bacteria. Ground water in some wells have 

high nitrate, iron, and arsenic concentrations. Frenzel 

(2000) described the occurrence of organochlorines, 

semivolatile organic compounds, and trace elements in 

streambed sediments and fish tissues at 15 sites in the 

basin during 1998. At most sites, semivolatile organic 

compounds and organochlorine compounds were 

either not detected or were detected at very low concentrations; however, arsenic, chromium, copper, and 

nickel appear to be at naturally high concentrations in 

the Cook Inlet Basin. Most of the analytical results for 

the ground-water study described in this report are tabulated in the USGS water-resources data report for 

water year 1999 (Bertrand and others, 2000) and are 

available also at URL <http://water.usgs.gov/ak/nwis/ 

nwis>.

Water-quality data for the first 20 NAWQA study 

units for the period 1992–95 were summarized by

Gilliom and others (1998), U.S. Geological Survey 

(1999b), Barbash and others (1999), Squillace and 

others (1999), and Nolan and Stoner (2000) and also 

are available at URL <http://water.usgs.gov/nawqa/ 

data>. More than 90 ground-water studies were conducted in these 20 study units.

Acknowledgments

The author expresses his sincere thanks to the 

many landowners who graciously allowed access to 

their property and sampling of water from their wells. 

Numerous landowners also allowed the plumbing in 

their homes to be modified so that a water sample 

could be obtained before treatment and before a pressure tank. This study could not have been completed 

without their cooperation. The cities of Kenai and 

Palmer, the Municipality of Anchorage, and the U.S. 

Army provided data about their wells and allowed us 

to sample water from their wells.

MAJOR WATER-QUALITY ISSUES

Ground water is an important source of water

for residents and businesses in the COOK study unit. 

About one-quarter of the public-water supply for 

Anchorage is from wells, and almost all water used

for commercial, industrial, and domestic uses outside 

Anchorage is from ground water. Ground water also 

provides year-round discharge to surface water and 

potentially transports contaminants that can result

in water-quality problems in streams and lakes. An 

understanding of the natural water quality and of the 

magnitude of changes in water quality caused by 

human activities is needed to evaluate the potential 

effects of contamination and to develop strategies to 

protect the quality of the resource.

Natural ground-water quality is determined by 

the mineralogy and chemical conditions of the soils 

and aquifer materials through which the water moves 

and by the length of time the water has been in contact 

with the soils and aquifer materials. Elevated concentrations of many naturally occurring minerals and of 

trace elements such as arsenic, iron, manganese, and 

radon may cause health or aesthetic problems and can 

render individual and community water supplies unusable or require that the water to be treated before use.

Human activities can influence the types and 

concentrations of many ground-water contaminants, 

such as nutrients (compounds of nitrogen and phosphorus) and organic compounds. Residential and agricultural land uses can contribute nutrients and organic 

compounds to ground water through leaching of fertilizers, pesticides, and petroleum products. Roadways 

and railroads can be the source of chloride (from 

applications of salt for deicing), of herbicides (applied 

to rights-of-way), and of VOCs (emitted to the air or 

spilled on the ground). Chemicals used by homeowners, such as household cleaners, paints, solvents, fuel 

oil, and gasoline, also can be a source of VOCs in 

ground water. Commercial and industrial establishments may also discharge VOCs and other substances 

to the atmosphere or to the ground. The Alaska 

Department of Environmental Conservation (1996, p. 

12) stated that petroleum products constitute the primary contaminant of water in Alaska. Petroleum products commonly enter the ground through leaking of 

tanks and distribution lines or spilling of product on 

the surface.
6 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

ENVIRONMENTAL SETTING AND 

HYDROLOGIC CONDITIONS

Water quality is affected by natural factors such 

as physiography, climate, geology, and soils and by 

human factors such as population and land use. The 

lands that drain into Cook Inlet Basin extend 39,325 

mi2 and include areas of rugged mountains, glaciers, 

forests, and wetlands as well as the city of Anchorage 

and multiple surrounding suburban communities. 

About 366,000 people—more than half of Alaska’s 

population—reside in the Cook Inlet Basin. Population density ranges from unpopulated remote regions 

to the densely populated Anchorage metropolitan area. 

Major roads traverse the eastern part of the basin, 

whereas the western part is sparsely populated and is 

accessed only by aircraft or boat. The 790-mi2 groundwater study area (fig. 2) includes the populated parts 

of lowland areas and contains most of the residents of 

the Municipality of Anchorage and the Kenai Peninsula and Matanuska–Susitna Boroughs. This study 

area consists of about 230 mi2 in the northwestern part 

of the Kenai Peninsula, about 190 mi2

 of Anchorage, 

and 370 mi2 of the Matanuska–Susitna Valley. At the 

present time, the areas near Wasilla and Palmer in the 

Matanuska–Susitna Valley and Kenai and Soldotna on 

the Kenai Peninsula are having the greatest population 

growth in the basin.

Most of the ground-water study area is in a transitional zone between wet maritime and continental 

climates (Brabets and others, 1999). This transitional 

zone has cold winters and warm summers. Anchorage 

has an average annual temperature of 6°C and an average annual precipitation of 15 in. (Arctic Environmental Information and Climate Center, 1989). However, 

the amount of precipitation falling in the Talkeetna, 

Chugach, and Kenai Mountains that bound the study 

area is much greater.

These mountains consist of structurally complex 

and variably metamorphosed consolidated sedimentary and igneous rocks. Some formations of sedimentary rocks, which are exposed in mountains outside the 

ground-water study area and are present beneath the 

study area, contain economically significant amounts 

of oil, natural gas, and coal.

Glacial, glacioestuarine, and alluvial deposits 

underlie the lowlands of Cook Inlet Basin and make 

up the most productive water-supply aquifers. These 

unconsolidated deposits were described by Freethey 

and Scully (1980), Schmoll and others (1999), Miller 

and others (1999), and Brabets and others (1999). 

These deposits range in thickness from less than 50

ft along the mountain fronts to greater than 1,000 ft 

beneath Cook Inlet and are made up of clay, silt, sand, 

gravel, and boulders. Large ground-water supplies 

generally can be developed where aquifer materials 

are saturated and predominantly coarse grained.

Beneath much of the lowland area of Anchorage 

is an extensive layer of silt and clay that was deposited 

in a large body of water in Cook Inlet Basin during 

glacial times. Its top surface is generally less than 100 

ft below land surface. This layer of fine-grained materials, as great as 200 ft thick, helps protect deeper 

aquifers from contamination and may create confined 

ground-water conditions.

Ground-water recharge occurs directly from precipitation that falls on the land surface above the aquifer and from streams, lakes, and wetlands. Groundwater flow in the aquifers is affected by topography 

and by the hydraulic characteristics of the aquifer system. Ground water generally flows toward Cook Inlet, 

but large amounts discharge to streams or are withdrawn by pumping. Brabets and others (1999, p. 44) 

estimated that in Anchorage, ground-water discharge 

from lowland aquifers into streams probably exceeds 

10 Mgal/d. The highest rates of pumping occur in 

Anchorage, Nikiski, Kenai, and Soldotna. The average 

pumpage from public-supply wells in Anchorage was 

about 7 Mgal/d in 1998. Industrial pumpage in Nikiski 

is about 3.5 Mgal/d, and pumpage of public-supply 

wells is about 1 Mgal/d in Kenai and about 1 Mgal/d 

in Soldotna.

Land uses were defined by the Municipality of 

Anchorage (2000) for the southern two-thirds of the 

Anchorage ground-water study area. During 1998, 

about 42 percent of this part of the Anchorage study 

area was owned and used by the military (Elmendorf 

Air Force Base and the U.S. Army Fort Richardson) or 

by Alaska Native corporations; 20 percent was classified as residential; 12 percent was classified as park; 

11 percent, as commercial, industrial, or institutional; 

11 percent, as intertidal or water bodies; and 4 percent, 

as transportation related (such as roadways, railways, 

and airports). The Matanuska–Susitna and Kenai parts 

of the study area do not contain major military installations but have significant areas of agriculture. The 

main crops are hay and oats, but potatoes and carrots 

are also cultivated in the Matanuska–Susitna area. 
METHODS OF INVESTIGATION 7

METHODS OF INVESTIGATION

The design and data-collection methods used for 

this study are similar to other NAWQA subunit surveys to provide consistency and comparability of 

results. The subunit consisted of unconsolidated glacial and alluvial aquifers beneath developed areas. 

One set of water samples was collected from 29 randomly selected sites during July to October 1999 and 

was analyzed to determine the occurrence and distribution of many natural and manmade substances 

within the subunit. Water samples also were collected 

from an additional five major public-supply wells. 

These two groups of sample sites are referred to as the 

subunit survey and public-supply survey in this report.

Well Selection

To obtain an unbiased and representative sampling across the subunit’s major aquifer systems, a 

geographic information system-based computer program (Scott, 1990) was used to divide the 790-mi2

ground-water study area into 30 equal areas called 

cells, and the program randomly selected a point in 

each cell. Existing water-supply wells that were as 

near as possible to each selected point were located by 

using water-well data in the USGS Ground-Water Site 

Inventory files and by field reconnaissance. Landowners near each selected point were contacted until a 

suitable well was found. The well needed to have construction information (a driller’s log containing depth, 

perforated interval, casing length, and geologic materials penetrated), be perforated or open in unconsolidated deposits, have a submersible pump, have a 

sampling point before any water-treatment systems 

and pressure tanks, and have a way to measure the 

depth to the water surface in the well (Lapham and 

others, 1995). Data from a cell in the northwestern part 

of the study area (well 17) are not included in this 

report because water-quality results indicate that at 

least some of the water sampled had been treated by a 

water softener even though water was collected before 

the pressure tank and water softener. The 29 remaining 

wells in the subunit survey range in depth from 24 to 

233 ft (table 1) and have a median depth of 88 ft. All 

wells were drilled and have steel casings; most are

6 in. in diameter and have pitless adapters that allow 

water pumped from the well to be piped to a house 

beneath the land surface to prevent freezing. 

Five of the subunit’s most productive public-supply wells—one in Palmer, three in Anchorage, and one 

in Kenai—also were sampled. These wells generally 

are deeper, have longer lengths of screen, and have 

turbine pumps that yield water at much greater rates 

than the wells in the subunit survey. Although the 

results from five samples are too few to statistically 

characterize water quality and were not randomly 

selected, the results give a general indication of the 

water quality in aquifers used for public supply.

The public-supply well sampled in Palmer 

pumped about 261 million gallons during 2000, about 

95 percent of the water distributed by the City of 

Palmer. The public-supply well sampled in Kenai 

pumped about 208 million gallons during 2000, about 

55 percent of the water distributed by the City of 

Kenai. During 2000, the three public-supply wells 

sampled in Anchorage (wells 32, 33 and 34) pumped 

about 210 million, 503 million, and 284 million gallons, respectively, and together accounted for about 46 

percent of the amount pumped by 12 wells in the 

Anchorage metropolitan area operated by Anchorage 

Water and Wastewater Utility.

Sample Collection

Water samples were collected and processed 

according to protocols developed by the NAWQA Program to minimize contamination during sampling and 

promote the collection of consistent ground-water data 

among NAWQA study units throughout the Nation 

(Koterba and others, 1995; U.S. Geological Survey, 

1999a). Water samples collected for this study were 

collected before any water-quality treatment and may 

not represent the water actually used within a home

or distributed for public supply. Many of the homes 

where water samples were collected had water-treatment equipment, such as iron and sediment filters and 

water softeners. Water from each of the public-supply 

wells has chlorine and fluoride added to it and is 

mixed with water from other sources during distribution.
8

Ground-WaterQuality,CookInletBasin,Alaska,1999

Table 1. Identification, location, and characteristics of sampled wells in Cook Inlet Basin, 1999[See figure 2 for geographic setting of wells. Clay or silt above well opening: Yes means open interval of well is overlain by clay, silt, or hardpan. Land use means general land use within 0.25-mile radius of well. Water level: D, value from driller’s log; E, estimated on basis of water level measured in nearby well; G, pressure gage; P, well being pumped; R, well recently pumped. NAD83, North American Datum of 1983 geodetic reference system]

Well

number

Station

identification

number

Local number

NAD83 

coordinates

(latitude, 

longitude)

Municipality

or borough

Use of

well

water

Clay

or silt

above

 well

opening

Land uses in

vicinity of well

Diameter

of well

casing

(inches)

Depth

of well

(feet)

Open

interval

(feet

below

land

surface)

Water level

(feet

below

 land

surface)

Altitude

of land

surface

 (feet

above

 sea 

level)

Subunit survey

1 602107151160901 SB00301213ADDD1 001 60°21'04.8" N., 

151°16'18.2" W.

Kenai Peninsula 

Borough

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), general–wetland, urban–residential, urban–other

6 95 90–95 55.45 106

2 602311151123701 SB00301104BBBC1 006 60°23'09.4" N.,

151°12'44.0" W.

Kenai Peninsula 

Borough

Domestic Yes Urban–residential, general–

forest (coniferous–deciduous, light silviculture), general–wetland, general–water

6 177 172–177 112.45 287

3 603216151114501 SB00501110CBAD2 008 60°32'13.2" N.,

151°11'52.0" W.

Kenai Peninsula 

Borough

Domestic Yes General–wetland, urban–

residential, general–water, general–forest (coniferous–deciduous, light silviculture)

6 128 128 -7.30 16

4 603332151110401 SB00501103ABAB1 002 60°33'32.5" N.,

151°11'04.2" W.

Kenai Peninsula 

Borough

Irrigation Yes Urban–developed land 

without major structures, general–forest (coniferous–deciduous, light silviculture), urban–residential, general–wetland

6 36 31–36 16.97 84

5 604328151104901 SB00701103DABC1 016 60°43'28.5" N.,

151°10'48.9" W.

Kenai Peninsula 

Borough

Domestic No General–forest (coniferous–

deciduous, light silviculture), general–water, urban–residential, general–wetland

6 32 32 3.60

(P)

98

6 613053150021801 SB01700432CDDA1 002 61°30'50.1" N.,

150°02'25.7" W.

Matanuska–

Susitna Borough

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), urban–residential, general–water

6 219 219 81.00 180

7 612421150044601 SB01500512ADDC1 003 61°24'20.2" N.,

150°04'44.8" W.

Matanuska–

Susitna Borough

Livestock No Agricultural (croplands), 

general–forest (coniferous–deciduous, light silviculture), agricultural (livestock), agricultural (farm residence and related buildings)

6 60 60 40.00 153
METHODS OF INVESTIGATION 9

8 612055150014801 SB01500432ACCB1 001 61°20'52.0" N.,

150°01'56.3" W.

Matanuska–

Susitna Borough

Institutional No Agricultural (croplands), 

general–forest (coniferous–deciduous, light silviculture)

6 67.3 56.3–67.3 44.20 152

9 603216151085401 SB00501111DABD1 002 60°32'14.9" N.,

151°08'59.3" W.

Kenai Peninsula 

Borough

Domestic Yes General–wetland, general–

water, urban–residential

6 90 90 4.48 25

10 603025150564001 SB00501024DACC1 016 60°30'23.2" N.,

150°56'46.9" W.

Kenai Peninsula 

Borough

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), urban–residential, urban–commercial

6 68 68 55.05 271

11 602600151084301 SB00401114CDBB1 004 60°25'59.6" N.,

151°08'45.1" W.

Kenai Peninsula 

Borough

Domestic Yes Urban–residential, general–

forest (coniferous–deciduous, light silviculture), agricultural (livestock)

6 110 105–110 88.60 250

12 610758149480501 SB01200315BCBC1 078 61°07'56.3" N.,

149°48'13.1" W.

Municipality of 

Anchorage

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), urban–residential, urban–developed land without major structures

6 233 233 182.25 360

13 610928149530301 SB01200306CABD1 019 61°09'24.6" N.,

149°53'03.8" W.

Municipality of 

Anchorage

Public

supply

Yes Urban–commercial, urban–

residential, general–forest (coniferous–deciduous, light silviculture)

8 75 70–75 35

(D)

103

14 612606149483901 SB01600333ADCA1 001 61°26'02.3" N.,

149°48'35.2" W.

Matanuska–

Susitna Borough

Domestic Yes General–wetland, general–

forest (coniferous–deciduous, light silviculture), general–water, urban–residential, urban–disturbed land

6 73.6 61–73.6 18.80 75

15 613053149565301 SB01700435CDDD1 002 61°30'48.9" N.,

149°56'38.9" W.

Matanuska–

Susitna Borough

Domestic No General–forest (coniferous–

deciduous, light silviculture), general–water, urban–residential

6 24 24 12.70 250

16 613227149483501 SB01700327BBBC1 001 61°32'25.4" N.,

149°48'45.9" W.

Matanuska–

Susitna Borough

Domestic Yes Urban–residential, general–

forest (coniferous–deciduous, light silviculture), urban–other

6 190 190 56.20 210

18 613550149453701 SB01700302ABDC1 006 61°35'45.9" N.,

149°45'46.6" W.

Matanuska–

Susitna Borough

Domestic Yes Urban–residential, general–

forest (coniferous–deciduous, light silviculture), general–wetland

6 121 121 82.70 298

19 612939149413201 SB01600207ADBD1 006 61°29'37.3" N.,

149°41'43.8" W.

Matanuska–

Susitna Borough

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), urban–residential, urban–other, general–wetland

6 100 100 67.00 300
10 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999 Table 1. Identification, location, and characteristics of sampled wells in Cook Inlet Basin, 1999—Continued [See figure 2 for geographic setting of wells. Clay or silt above well opening: Yes means open interval of well is overlain by clay, silt, or hardpan. Land use means general land use within 0.25-mile radius of well. Water level: D, value from driller’s log; E, estimated on basis of water level measured in nearby well; G, pressure gage; P, well being pumped; R, well recently pumped. NAD83, North American Datum of 1983 geodetic reference system] Well number Station identification number Local number NAD83 coordinates (latitude, longitude) Municipality or borough Use of well water Clay or silt above well opening Land uses in vicinity of well Diameter of well casing (inches) Depth of well (feet) Open interval (feet below land surface) Water level (feet below land surface) Altitude of land surface (feet above sea level) Subunit survey—Continued 20 611726149442801 SB01400324BCDB1 001 61°17'27.1" N., 149°44'37.9" W. Municipality of Anchorage Domestic Yes General–forest (coniferous– deciduous, light silvi- culture), general–water, general–wetland, urban– developed land without major structures 6 85 75–85 18.09 100 21 611438149432301 SB01300301DACB1 003 61°14'35.4" N., 149°43'30.4" W. Municipality of Anchorage Public supply Yes Urban–disturbed land, gen- eral–water 16 152 132–152 103(P) 251 22 610759149422301 SB01200313BCBD2 053 61°07'57.0" N., 149°44'30.0" W. Municipality of Anchorage Domestic Yes Urban–residential, general– forest (coniferous–decid- uous, light silviculture) 6 211 211 202 733

23 612130149325501 SB01500225DBCD2 012 61°21'28.8" N.,

149°33'04.7" W.

Municipality of 

Anchorage

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), urban–residential, general–water, urban–other

6 129 119–129 107.35 360

24 613151149015401 SA01700226DDBB1 017 61°31'49.3" N.,

149°02'03.2" W.

Matanuska–

Susitna Borough

Domestic No Urban–residential, general–

forest (coniferous–deciduous, light silviculture)

6 50 50 35.34 98

25 613257149345401 SB01700223DBBA1 012 61°32'53.5" N.,

149°35'02.7" W.

Matanuska–

Susitna Borough

Domestic No Urban–residential, general–

forest (coniferous–deciduous, light silviculture)

6 213 213 189.6 418

26 613428149044501 SA01700210CCAA2 018 61°34'26.3" N.,

149°04'53.8" W.

Matanuska–

Susitna Borough

Domestic No Agricultural (croplands), 

urban–residential, general–forest (coniferous–deciduous, light silviculture), agricultural (livestock)

6 81 81 71.90 189

27 613530149244101 SB01700102CBAD1 054 61°35'28.7" N.,

149°24'49.7" W.

Matanuska–

Susitna Borough

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), urban–residential, urban–other

6 60 60 40.70 369

28 613553149253601 SB01700103ABDA1 004 61°35'50.7" N.,

149°25'44.3" W.

Matanuska–

Susitna Borough

Domestic Yes Urban–residential, general–

forest (coniferous–deciduous, light silviculture)

6 141 141 97.17 467
METHODS OF INVESTIGATION 11

29 613716149394101 SB01800229DAAA3 001 61°37'15.6" N.,

149°39'50.1" W.

Matanuska–

Susitna Borough

Domestic Yes General–forest (coniferous–

deciduous, light silviculture), urban–residential, general–water

6 80 80 60.25 336

30 613847149131801 SA01800114CDAA1 010 61°38'46.1" N.,

149°13'28.8" W.

Matanuska–

Susitna Borough

Domestic Yes Agricultural (croplands), 

general–forest (coniferous–deciduous, light silviculture), general–wetland, urban–residential, agricultural (farm residence and related buildings)

6 61 50–55 22.50 541

Public-supply survey

31 613509149053701 SA01700204DCDD1 012 61°35'08.8" N.,

149°05'47.4" W.

Matanuska–

Susitna Borough

Public 

supply

No Agricultural (croplands), 

urban–commercial, general–forest (coniferous–deciduous, light silviculture), urban–other

12 186 151–171 106 221

32 611331149492901 SB01300309CDCD1 001 61°13'28.7" N.,

149°49'38.6" W.

Municipality of 

Anchorage

Public 

supply

Yes Urban–commercial, 

general–forest (coniferous–deciduous, light silviculture), urban–developed land without major structures, urban–residential, urban–disturbed land

20 329 270–322 61.9

(E)

143

33 611106149522802 SB01300330DBDD2 030 61°11'04.9" N.,

149°52'34.1" W.

Municipality of 

Anchorage

Public 

supply

Yes Urban–commercial, urban–

disturbed land, general–forest (coniferous–deciduous, light silviculture)

16 268 232–268 32

(G)

110

34 611026149432002 SB01300336DABB2 009 61°10'22.5" N.,

149°43'28.2" W.

Municipality of 

Anchorage

Public 

supply

Yes General–forest (coniferous–

deciduous, light silviculture), urban–disturbed land

16 89.5 70–89 31.5

(E)

398

35 603405151081201 SB00601136BCDC1 008 60°34'03.4" N.,

151°08'26.2" W.

Kenai Peninsula 

Borough

Public 

supply

Yes General–wetland, general–

forest (coniferous–deciduous, light silviculture), urban–commercial

12 420 348–420 22

(R)

79
12 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Sample Analyses

Analyses for major ions, nutrients, trace elements, radiochemicals, VOCs, and pesticides were 

done by the USGS National Water-Quality Laboratory 

(NWQL) in Denver, Colo. Analyses for CFC compounds and environmental isotopes were performed in 

USGS laboratories in Reston, Va. Analyses for tritium 

were done by Lamont–Doherty Earth Observatory of 

Columbia University in Palisades, N.Y. Analyses for 

radium were performed by Quanterra Analytical Services in Richland, Wash. The analytical methods that 

were used are summarized in table 2.

Samples collected for alkalinity, major ions, 

nutrients, trace elements, and some radioisotopes 

(alpha and beta activities and radium) were filtered 

onsite by using capsule filters that have 0.45-μm 

pores. Samples for dissolved organic carbon were

filtered by using silver-membrane filters that have 

0.45-μm pores. Pesticides samples were filtered by 

using 0.7-μm baked-glass-fiber filters. All other analyses were made by using unfiltered water samples. All 

sampling and filtering equipment was decontaminated 

after each use according to methods described by Koterba and others (1995).

Analytical results were evaluated in the context 

of minimum reporting levels and method detection 

limits established by each laboratory (Zaugg and

1Analytical method was modified from that of Werner and others’ (1996).

Table 2. Methods used to analyze water from wells in Cook Inlet Basin, 1999

[—, not applicable or none]

Constituent or constituent group U.S. Geological Survey

schedule or laboratory code Method of analysis Reference

Field determinations

Water temperature, pH, specific

conductance, dissolved oxygen,

 alkalinity

— Various U.S. Geological Survey (1999a)

Inorganic constituents

Major ions Schedule 2750 Various Fishman and Friedman (1989)

Nutrients Schedule 2752 Various Fishman and Friedman (1989)

Metals and trace elements Schedule 2703 Inductively coupled plasma mass 

spectrometry

Fishman and Friedman (1989)

Dissolved organic carbon Schedule 2085 Ultraviolet-promoted persulfate oxidation 

and infrared spectrometry

Brenton and Arnett (1993)

Organic compounds

Pesticides Schedule 2001 Solid-phase extraction and analysis by gas 

chromatography–mass spectrometry with 

selected ion monitoring

Zaugg and others (1995)

Laboratory code 9060 Solid-phase extraction and high-performance 

liquid chromatography1

Werner and others (1996)1

Volatile organic compounds Schedule 2020 Purge-and-trap isolation and concentration; 

capillary-column gas chromatography–

mass spectrometry

Rose and Schroeder (1995)

Chlorofluorocarbons Schedule 1173 Purge-and-trap gas chromatography Plummer and Busenberg (1999)

Radioisotopes and environmental isotopes

Tritium Laboratory code 2112 Electrolytic enrichment and liquid 

scintillation

Ostlund and Dorsey (1977) 

Tritium–helium ratio Schedule 1033 Electrolytic enrichment and liquid 

scintillation

Ostlund and Dorsey (1977) 

Radon-222 Laboratory code 1369 Liquid scintillation American Society for Testing 

and Materials (1996) 

Deuterium–hydrogen ratio Schedule 1173 Hydrogen equilibrium at 30o

C Coplen and others (1991)

Oxygen-18–oxygen-16 ratio Schedule 1173 Carbon dioxide equilibrium at 25oC Epstein and Mayeda (1953)

Gross alpha and beta radiation 

and radium

Schedule 1263 Gamma-ray spectrometry using high-purity 

germanium detector

—
METHODS OF INVESTIGATION 13

others, 1995; Childress and others, 1999). In some 

instances in this report, concentration values for individual compounds are lower than the method detection 

limits. If a constituent may be present in a sample at a 

concentration less than the method detection limit, the 

listed concentration was estimated. Estimated values 

indicate probable analyte detection; however, the 

reported concentration value was not quantifiable. 

Most of the analytical results were reported previously 

by Bertrand and others (2000), are stored in the USGS 

National Water Information System database, and are 

accessible on the Internet at URL <http://water.usgs

.gov/ak/nwis/qwdata>.

Quality Control

Quality-assurance–quality-control samples were 

collected to evaluate the accuracy and precision of 

concentrations of constituents measured in groundwater samples and to determine if samples were contaminated during their collection, processing, and 

analysis. Blank samples, replicate samples, and spike 

samples were collected, preserved, and analyzed by 

using the same methods and equipment as those used 

for the environmental ground-water samples. The 

USGS NWQL also spiked selected samples for 

selected VOCs and pesticides. In general, reported 

concentrations of most constituents are considered 

accurate and precise, but the reported frequencies

of detection and concentrations of ammonia, nitrate, 

phosphorus, copper, iron, manganese, and toluene

may be higher than actual.

Field blanks consisted of waters that contained 

neither inorganic constituents nor organic compounds 

and that had been pumped through the sampling 

equipment and discharge lines to determine whether 

cleaning procedures eliminated contamination 

between sites and to ensure that field methods, sample 

shipment, and laboratory procedures had not contaminated samples. Results from three inorganic and two 

organic field blanks collected after sampling wells 3, 

30, and 34 showed that for most constituents, chemical 

contaminants were not being introduced as a result of 

sample collection and equipment decontamination 

procedures. However, calcium, magnesium, silica, 

ammonia, nitrate, phosphorus, copper, iron, manganese, toluene, and dichloromethane were present in 

field blanks in small concentrations (table 3). The concentrations of ammonia, nitrate, phosphorus, copper, 

iron, manganese, and toluene in field blanks were similar to those measured in some ground-water samples. 

1Estimated value.

Table 3. Constituents detected in quality-control samples from Cook Inlet Basin, 1999

[See table 2 regarding analytical methods used. <, less than]

Constituent Unit

Number of

 quality-control

 samples

Number of qualitycontrol samples

having detectable

 concentrations

Minimum

reporting level

or method

detection limit

Highest concentration

in quality-control

samples

Range of concentrations

in ground-water samples

Field Blanks

Calcium Milligram per liter 3 3 0.02 0.01 4.4–77

Magnesium Milligram per liter 3 1 .001 .001 2.1–18

Silica (as SiO2) Milligram per liter 3 2 .05 .043 5.9–46

Ammonia plus organic 

nitrogen (as N)

Milligram per liter 2 2 .05 1.05 <0.1–0.8

Nitrite plus nitrate (as N) Milligram per liter 2 1 .05 . 15 <0.05–4.8

Phosphorus (as P) Milligram per liter 2 1 .004 .004 <0.004–0.38

Copper Microgram per liter 3 1 1 .22 <1–15

Iron Microgram per liter 3 1 3 11.2 <10–18,000

Manganese Microgram per liter 3 1 1 .13 <1–1,460

Toluene Microgram per liter 2 2 .05 .087 <0.05–0.77

Dichloromethane (as 

methylene chloride)

Microgram per liter 2 1 .38 .066 <0.38

Trip blanks

Toluene Microgram per liter 2 1 0.05 0.043 <0.05–0.77
14 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

As a result, environmental data for these constituents 

may be biased, and interpretations for these constituents, particularly at low levels, therefore requires caution. The presence of detectable concentrations of 

some constituents may be the result of one or more of 

the following: use of contaminated sample-preparation 

equipment, such as filters, sample bottles, or preservative; carryover from field or laboratory equipment; or 

the analytical method used.

Trip blanks consisted of sample vials filled with 

VOC-free water in the USGS Anchorage Field Office 

laboratory and transported to the field and submitted 

to the laboratories with environmental samples. Trip 

blanks, used to verify that VOC samples were not contaminated during storage, sampling, or shipment to the 

laboratory, were transported during the sampling of 

wells 5 and 24. Toluene detected in one of two trip 

blanks had an estimated concentration of 0.043 μg/L. 

Sequential replicate samples are a second set of 

water samples collected and preserved immediately 

after an environmental sample, by the same techniques

and equipment. Results from the replicate samples at 

wells 10, 22, and 24 indicate good agreement between 

measured concentrations: Most paired values were 

within 10 percent, although several constituents had 

relative differences between environmental and replicate samples of more than 10 percent (table 4). However, small concentration differences may result in 

large relative-percentage differences when environmental- and replicate-sample concentrations are also 

small.

Laboratory spiking of samples also were performed by NWQL to determine the precision and 

accuracy of analyte recovery in the sample matrix and 

to evaluate the effectiveness of the analytical methods 

for selected analytes. Recoveries for selected VOCs 

(1,2-dichloroethane, toluene, and 1,4-bromofluorobenzene) ranged from 84 to 119 percent; recoveries for 

selected pesticides (diazinon and alpha-HCH) ranged 

from 72 to 124 percent. These results of laboratory 

spiking indicate that matrix effects were minor, and 

the analytical methods were effective.

Table 4. Constituents that have relative-percentage differences greater than 10 percent in replicate samples 

from Cook Inlet Basin

[See table 2 regarding analytical methods used. <, less than]

1Relative-percentage difference equals difference between concentrations of environmental and replicate samples divided by average of concentrations of environmental and replicate samples.

Constituent

Number of 

replicate

samples

Concentration Relativepercentage 

difference1

(percent)

Number of replicate 

samples that have 

relative-percentage 

differences1 greater 

than 10 percent

Environmental

sample

Replicate

sample Unit

Potassium 2 1 .9 Milligram per liter 11 1

Bromide 2 .02 .01 Milligram per liter 67 1

Aluminum 2 5 <1 Microgram per liter 133 1

Copper 2 1 2 Microgram per liter 67 1

Zinc 2 56 32 Microgram per liter 55 1

Radon-222 2 180

220

210

190

Picocurie per liter 15

15

2

Dissolved organic carbon 2 .6

.6

.7

.5

Milligram per liter 15

18

2
WATER-QUALITY STANDARDS AND GUIDELINES 15

WATER-QUALITY STANDARDS AND 

GUIDELINES 

The concentrations of constituents determined 

during this study are compared with current U.S. Environmental Protection Agency (2000, 2001) drinkingwater regulations and guidelines. Drinking-water standards include the primary (MCL), secondary (SMCL), 

and proposed maximum contaminant levels; action 

levels; and health advisories. The USEPA drinkingwater standards are defined as the permissible level of 

a contaminant in water delivered to users of a public 

water system. An MCL is an enforceable standard and 

is established on the basis of health effects, treatment 

feasibility, cost of treatment, and analytical detection. 

An SMCL is a nonenforceable guideline based on 

esthetics and is established for constituents that can 

adversely affect the odor or appearance of water and 

result in the discontinuation of the water’s use. Action 

levels are considered the lowest level to which water 

systems can reasonably be required to control a contaminant should it occur in drinking water. Health 

advisories are nonregulatory levels of contaminants in 

drinking water that may be used for guidance in the 

absence of regulatory limits. They consist of estimates 

of the highest concentrations that would result in no 

known or anticipated health effects (or for carcinogens, a specified cancer risk), determined for a child

or for an adult for various exposure periods. A lifetime 

health advisory is established for the part of an individual’s lifetime exposure that is attributed to drinking 

water and is considered protective against noncarcinogenic adverse health effects over a lifetime exposure 

(70 years). 

PHYSICAL PROPERTIES AND FIELD 

MEASUREMENTS 

When possible, the depth to water in each well 

was measured before the pump was turned on for sampling. Water levels ranged from 7.3 ft above land surface in a well perforated in a confined aquifer near the 

mouth of the Kenai River to 202 ft below land surface 

in a well along the mountain front in Anchorage. As 

water was being pumped from the well, measurements 

of water temperature, specific conductance, dissolved 

oxygen, pH, and alkalinity were made to help determine some basic chemical characteristics of the water; 

the stabilized values for each site are summarized in 

table 5 and are presented in more detail in appendix 1. 

1 U.S. Environmental Protection Agency (2000).

Table 5. Statistical summary of physical properties and 

field measurements for water sampled from wells in Cook 

Inlet Basin, 1999

[Number in parentheses to left of property or constituent is number used by both 

U.S. Environmental Protection Agency and U.S. Geological Survey to identify 

parameter in computerized data bases. See table 2 regarding analytical methods 

used. SMCL, secondary maximum contaminant level. >, greater than; <, less than; 

—, no criteria or not applicable]

Survey

network

Number of

analyses

Value Drinkingwater

standard Minimum Median Maximum 1

(72019) Water level (feet below land surface)

Subunit 29 -7.3 56 202 —

Public supply 5 22 32 106 —

(72008) Well depth (feet below land surface)

Subunit 29 24 90 233 —

Public supply 5 90 268 420 —

(72004) Pumpage period (minutes)

Subunit 29 30 60 >300,000 —

Public supply 5 30 90 210 —

(00059) Flow rate (gallons per minute)

Subunit 29 5 5 725 —

Public supply 5 650 1,200 1,800 —

(00010) Water temperature (degrees Celsius)

Subunit 29 3.0 4.0 9.5 —

Public supply 5 2.5 4.0 5.0 —

(00400) pH (standard units)

Subunit 29 6.7 7.9 8.3 —

Public supply 5 7.1 8.0 8.4 —

— — — — — 6.5 (SMCL)

(minimum)

— — — — — 8.5 (SMCL)

(maximum)

(00095) Specific conductance (microsiemens per centimeter at 25oC)

Subunit 29 77 255 1,750 —

Public supply 5 168 201 310 —

(00300) Dissolved oxygen (milligrams per liter)

Subunit 29 0.1 0.6 11.8 —

Public supply 5 <0.1 1.6 11 —

(39086) Alkalinity (milligrams per liter as CaCO3)

Subunit 29 34 127 384 —

Public supply 5 77 100 103 —
16 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Ground water in the Cook Inlet Basin is cool: About 

90 percent of the wells sampled yielded water having 

temperatures less than 6°C. Most wells yielded water 

having specific-conductance values less than 300 

μS/cm, indicating low dissolved-solids contents (less 

than about 180 mg/L). The highest values of specific 

conductance (946 and 1,750 μS/cm) were from wells 

near the mouth of the Kenai River. Dissolved-oxygen 

concentrations of less than 1 mg/L indicate chemically 

reducing conditions and were observed in 15 of 29 

wells in the subunit survey and in 1 public-supply 

well. Under reduced conditions, ions such as arsenic, 

iron, and manganese are more soluble in ground water. 

Observed pH values ranged from 6.7 to 8.4 units. 

Alkalinity, a measure of the capacity of the substances 

dissolved in the water to neutralize acid, ranged from 

34 to 384 mg/L as CaCO3 for filtered samples.

MAJOR IONS

Water samples were analyzed for the following 

major inorganic constituents: calcium, magnesium, 

sodium, potassium, sulfate, chloride, fluoride, bromide, and silica (appendix 2). Bicarbonate concentration was determined by alkalinity titration. Most 

ground-water samples had low to moderate dissolvedsolids concentrations. However, the SMCL for dissolved solids, 500 mg/L, was exceeded in samples 

from two wells (3 and 9) near the mouth of the Kenai 

River. Summary statistics for the major constituents 

and USEPA drinking-water standards are listed in 

table 6. 

The dominant positively charged compounds 

(cations) include calcium, magnesium, sodium, and 

potassium. Calcium in drinking water has no detrimental health effects but contributes to the hardness

of water. Calcium and magnesium are both essential 

elements for plants and animals. Sodium and potassium are present in many different types of rocks, but 

potassium is slightly less common than sodium in 

igneous rock and more abundant in sedimentary rocks. 

Sodium tends to remain in solution once it has been 

dissolved, whereas potassium exhibits a strong tendency to be reincorporated; thus, the concentration of 1

 U.S. Environmental Protection Agency (2000).

Table 6. Statistical summary of major-ion concentrations in 

water sampled from wells in Cook Inlet Basin, 1999

[Number in parentheses to left of constituent is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. MCL, maximum contaminant level; SMCL, secondary 

maximum contaminant level. See table 2 regarding analytical methods used. <, less 

than; —, none or not applicable]

Survey

network

Number

of

analyses

Concentration in sample

(milligrams per liter)

Drinkingwater

standard1

(milligrams

per liter) Minimum Median Maximum

(00915) Calcium

Subunit 29 4.4 40 77 —

Public supply 4 6.3 28 56 —

(00925) Magnesium

Subunit 29 2.1 6.1 18 —

Public supply 4 4.1 6.5 7.7 —

(00930) Sodium

Subunit 29 2.0 3.6 360 —

Public supply 4 3.2 5.8 34 —

(00935) Potassium

Subunit 29 0.25 0.95 13 —

Public supply 4 .89 .95 4.2 —

(00453) Bicarbonate, as HCO3

Subunit 29 42 155 468 —

Public supply 5 94 122 126 —

(00945) Sulfate

Subunit 28 <0.1 3.0 55 —

Public supply 4 .3 9.1 62 —

— — —— — 250

(SMCL)

(00940) Chloride

Subunit 28 1.1 3.9 500 —

Public supply 4 .6 4.3 9.3 —

— — —— — 250

(SMCL)

(00950) Fluoride

Subunit 28 <0.1 <0.1 0.2 —

Public supply 4 <.1 <.1 .3 —

— — —— — 4

(MCL)

— — —— — 2

(SMCL)

(71870) Bromide

Subunit 28 <0.01 <0.01 0.87 —

Public supply 4 <.01 <.01 .02 —

(00955) Silica

Subunit 29 5.9 14 44 —

Public supply 4 6.3 13 46 —

(70300) Dissolved solids, residue at 180oC

Subunit 28 77 161 986 —

Public supply 4 119 147 213 —

— — — — — 500 (SMCL)
NUTRIENTS AND DISSOLVED ORGANIC CARBON 17

potassium in most natural water is much lower than 

that of sodium (Hem, 1985). Sodium concentrations 

were greatest in ground water near the mouth of the 

Kenai River. Potassium concentrations in most samples were low, generally less than 1 mg/L.

The dominant negatively charged compounds 

(anions) include bicarbonate, sulfate, chloride, fluoride, and bromide. Bicarbonate is produced in the soil 

zone from the reaction of carbon dioxide and water 

and from the dissolving of calcium carbonate in rocks. 

Bicarbonate is commonly a dominant anion in shallow, recently recharged ground water. Sulfate in 

ground water is derived mostly from the weathering of 

sedimentary and igneous rocks and from biochemical 

processes. Concentrations of sulfate were less than 5 

mg/L in water from wells on the Kenai Peninsula and 

from wells in the western Matanuska–Susitna area. 

The highest sulfate concentrations, ranging from 52 to 

62 mg/L, were in water samples from three wells (24, 

26, and 31) near the Matanuska River. Wells sampled 

in Anchorage yielded water samples having intermediate sulfate concentrations, ranging from 7.1 to 19 

mg/L. Most wells yielded water samples that had fluoride concentrations less than 0.1 mg/L.

Chloride concentrations were typically less than 

5 mg/L. However, well 3 near the mouth of the Kenai 

River yielded water having a chloride concentration 

that exceeded the SMCL standard of 250 mg/L. Water 

samples collected for previous studies in this coastal 

area also had sodium and chloride concentrations 

greater than 250 mg/L (Glass, 1996). This brackish 

ground water may be remnant from the time when a 

larger ancestral Cook Inlet covered the area (Glass, 

1999). Seawater intrusion due to withdrawals of 

ground water is unlikely because the altitudes of water 

levels in wells in this area are more than 20 ft above 

sea level.

Silica concentrations in water from wells in 

Anchorage and the Matanuska–Susitna areas ranged 

from 6 to 27 mg/L. Highest values, ranging from 26 to 

46 mg/L, were observed in water samples from wells 

on the Kenai Peninsula.

Trilinear diagrams are a means of indicating general similarities and differences in the composition of 

water from certain geologic units (Freeze and Cherry, 

1979). Percentages of the total milliequivalents per 

liter (the number of moles of solute, multiplied by the 

valence of the solute species, in 1 liter of solution) of 

the dominant cations and anions in each water sample 

are shown in figure 3. Also shown are the combined 

cation and anion composition of the water, which is 

derived from projecting the data from the separate triangular cation and anion plots. Most water samples 

from wells in the Anchorage and Matanuska–Susitna 

areas had calcium as their dominant cation and bicarbonate as the dominant anion. Magnesium was the 

second-most dominant cation, commonly making up 

10 to 40 percent of the positive ions. Water from some 

wells on the Kenai Peninsula had greater proportions 

of sodium and chloride. The proportion of sulfate in 

most samples was low; only three wells (24, 26, and 

31) in the eastern Matanuska–Susitna area yielded 

waters having sulfate composing greater than 20 percent of the anions.

NUTRIENTS AND DISSOLVED ORGANIC 

CARBON

Precipitation, plant residues, and aquifer minerals 

generally contribute low concentrations of nitrate and 

phosphate to ground water. However, contributions 

from human sources, such as domestic and agricultural 

fertilizers and effluent from domestic septic systems, 

can increase nutrient concentrations significantly. 

Nutrients in sufficiently high concentrations can cause 

excessive algal growth in streams or, in extreme cases, 

be toxic to aquatic life and hazardous to human health. 

Nutrient concentrations in ground water sampled during 1999 did not exceed any drinking-water standard 

(table 7 and appendix 3) but may indicate contributions from human sources in some areas. 

The solubility of nitrogen is affected by the oxidation state of the ground water or aquifer. Nitrogen in 

ground water containing dissolved oxygen commonly 

is present as nitrate, whereas nitrogen in water having 

no or only small amounts of dissolved oxygen might 

not be present as nitrate owing to conversion of nitrate 

to nitrogen gas, nitrite, ammonia, or ammonium. 

Ammonia is less common than nitrate and nitrite. 

Nationally, the median ammonia concentration (quantified as measured nitrogen) in ground water in major 

aquifers is 0.02 mg/L (Nolan and Stoner, 2000). In

the Cook Inlet Basin, concentrations of ammonia were 

less than the minimum reporting level of 0.02 mg/L in 

23 of 34 ground-water samples. The highest concentrations of ammonia observed, 0.81 and 0.80 mg/L, 

were from water samples from two wells (3 and 9) 

near the mouth of the Kenai River and were far below 

the 30 mg/L health advisory.
18 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

EXPLANATION

Kenai Peninsula Borough

Municipality of Anchorage

Matanuska−Susitna Borough

Subunit survey

Public-supply survey

Subunit survey

Public-supply survey

Subunit survey

Public-supply survey









PERCENT

PERCENT

PERCENT

ANIONS

Cl + SO4

Cl + SO4 HCO3

HCO3

HCO3

+ SO4

Ca +Mg

Ca +Mg + Na + K

Na + K + Ca + Mg

Na + K

SO4

CO3 + HCO3 Cl

Chloride

type

Sulfate

type

Bicarbonate

type

No

dominant

type

CATIONS

Ca Na + K

Mg

Magnesium

type

Calcium

type

Sodium

type or

potassium

type

No

dominant

type

No

dominant

type

10

90

50

50

90

10

10

10

50

90 90

50

50

50 50

50

Ca+Mg

Na + K

CO3 + HCO3

Cl+SO4

Mg SO4

Ca+Mg

Cl+SO4

PERCENT

PERCENT

PERCENT

SO4

CO3 + HCO3 Cl, F, NO2 Ca Na + K +NO3

Mg

50

50

50

50 50

50

50

50 50

50

Na + K

CO3 + HCO3

SO4 Mg
NUTRIENTS AND DISSOLVED ORGANIC CARBON 19

Nitrite concentrations in undeveloped areas are 

commonly very low, typically less than 0.2 mg/L as N, 

and they represent only a small fraction of the total 

nitrogen in the system. All nitrite concentrations in 

ground-water samples were at or below the minimum 

reporting level of 0.01 mg/L as N. The MCL for nitrite 

is 1.0 mg/L.

Nitrate is the primary form of nitrogen dissolved 

in ground water. In this report, nitrate refers to the sum 

of nitrite plus nitrate. The national background concentration for nitrate in shallow ground water in undeveloped areas considered to be minimally affected by 

1U.S. Environmental Protection Agency (2000).

Table 7. Statistical summary of nutrient and dissolved organic carbon concentrations in water sampled from wells in Cook Inlet Basin, 1999

[Number in parentheses to left of constituent is number used by both U.S. Environmental Protection Agency

and U.S. Geological Survey to identify parameter in computerized data bases. See table 2 regarding analytical 

methods used. MCL, maximum contaminant level. <, less than; —, none or not applicable]

Survey

network

Number of analyses Concentration

(milligrams per liter)

Criterion1

(milligrams per liter)

Total

Resulting in

concentrations

less than

minimum

reporting level

Minimum Median Maximum

Drinkingwater

standard

Lifetime

health

advisory

(00608) Ammonia, as N

Subunit 29 19 <0.02 <0.02 0.81 — —

Public supply 5 4 <.02 <.02 .31 — —

— — — — — — — 30

(00623) Ammonia plus organic nitrogen, as N

Subunit 29 18 <0.1 <0.1 0.8 — —

Public supply 5 4 <.1 <.1 .3 — —

(00631) Nitrite plus nitrate, as N

Subunit 29 12 <0.05 0.12 4.8 — —

Public supply 5 1 <.05 .25 2.5 — —

— — — — — — 10 (MCL) —

(00613) Nitrite, as N

Subunit 29 27 <0.01 <0.01 0.01 — —

Public supply 5 5 <.01 <.01 <.01 — —

— — — — — — 1 (MCL) —

(00666) Phosphorus, as P

Subunit 29 11 <0.004 0.011 0.38 — —

Public supply 5 2 <.004 .014 .37 — —

(00671) Orthophosphate, as P

Subunit 29 13 <0.01 0.01 0.43 — —

Public supply 5 3 <.01 <.01 .45 — —

(00681) Dissolved organic carbon

Subunit 29 0 0.3 0.9 2.1 — —

Public supply 5 0 .3 .4 1.9 — —

Figure 3. Major-ion composition of 

water sampled from wells in Cook 

Inlet Basin, 1999.
20 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

agriculture, urbanization, and associated land uses is 

estimated to be about 2 mg/L as N (U.S. Geological 

Survey, 1999b, p. 34). Nitrate concentrations greater 

than about 3 mg/L may be indicative of human sources 

(Madison and Brunett, 1985). Ground-water samples 

from wells in the Cook Inlet Basin generally had low 

nitrate concentrations; 13 of 34 samples had concentrations less than 0.05 mg/L. Nitrate concentrations 

were highest in water from wells in the eastern part of 

Anchorage and were as great as 4.8 mg/L. Water from 

well 34, a public-supply well in a relatively undeveloped area in the eastern part of Anchorage, had a concentration of 2.5 mg/L. The MCL for dissolved nitrate 

is 10 mg/L as N.

To discourage excessive biotic growth in flowing 

water, total phosphorus concentrations (as P) should 

not exceed 0.1 mg/L. In the Cook Inlet Basin, phosphorus concentrations generally were low; 16 of 34 

samples had concentrations of dissolved orthophosphate less than 0.01 mg/L. The highest concentrations 

observed, 0.43 and 0.45 mg/L, were from two wells

(9 and 35) on the Kenai Peninsula. These high phosphorus concentrations are unlikely to have resulted 

from human activities because the openings for both 

wells are beneath a thick layer of clay. 

DOC in ground water can result from the partial 

oxidation of organic matter in the soil zone or in the 

aquifer. Naturally occurring organic matter in water 

and DOC can form complexes that affect metal solubilities, participate in reduction reactions, and serve as 

nutrients for microorganisms that mediate chemical 

processes (Hem, 1985). These processes commonly 

decrease dissolved oxygen and sulfate concentrations 

but may increase the amounts of arsenic, iron, and 

manganese dissolved in water. Naturally occurring 

organic matter can also cause taste, odor, or color 

problems in water and serve as precursors to the formation of trihalomethane compounds, which result 

from chlorination in water-treatment processes. DOC 

was detected in water at all sites, and concentrations 

did not have large spatial variations throughout the 

study unit. Concentrations of DOC ranged from 0.3 to 

2.1 mg/L. Freeze and Cherry (1979) reported that concentrations of DOC in ground water most commonly 

range from 0.1 to 10 mg/L.

TRACE ELEMENTS

Trace elements are inorganic chemicals commonly occurring in small amounts in natural water. In 

the COOK study unit, concentrations of aluminum, 

antimony, beryllium, cadmium, chromium, cobalt, 

lead, molybdenum, nickel, selenium, silver, and uranium dissolved in ground water were generally low, 

less than 5 μg/L (table 8 and appendix 4). Arsenic, 

barium, copper, iron, manganese, and zinc were 

present in some samples at concentrations greater than 

5 μg/L. Frenzel (2000) reported that arsenic, chromium, copper, and nickel appear to be at naturally 

large concentrations in streambed sediments in the 

Cook Inlet Basin, when compared with concentrations 

in streambed sediments in other NAWQA studies.

Naturally occurring arsenic commonly is found 

in some volcanic tuffs and ash; adsorbed to and coprecipitated with metal oxides, especially iron oxides; 

associated with the sulfide minerals pyrite and arsenopyrite; and associated with organic carbon (Welch and 

others, 2000). The unconsolidated aquifer materials 

within the COOK study unit may contain naturally 

large concentrations of arsenic. Concentrations of 

arsenic in streambed sediments ranged from 5.2 to 44 

μg/g (dry weight) at 14 sites in the basin and exceeded 

the median concentration at NAWQA streambedsediment sites sampled from 1992 to 1995, 6.35 μg/g, 

at 13 of 14 sites (Frenzel, 2000). The chemical reduction and dissolution of iron oxide in the aquifer materials, possibly through reaction with organic matter, also 

may allow high arsenic concentrations in ground water 

in some parts of the study unit. Commonly, wells

that yielded water having elevated concentrations of 

arsenic also yielded water having elevated concentrations of iron and manganese and low concentrations of 

dissolved oxygen and nitrate.

Long-term exposure to arsenic in drinking water 

can lead to cancer of the skin, lungs, bladder, and kidney as well as skin changes such as thickening and 

change in pigmentation (World Health Organization, 

2001). The proposed MCL for arsenic is 10 μg/L (U.S. 

Environmental Protection Agency, 2001); of the 34 

wells sampled, 6 (18 percent) had concentrations 

exceeding 10 μg/L. Glass (1999) reported that the
PESTICIDES 21

median dissolved arsenic concentration in water from 

69 wells previously sampled in the northern part of the 

Kenai Peninsula was 7 μg/L; the highest concentration 

reported was 94 μg/L. Concentrations of arsenic in 

water from the eight wells sampled on the Kenai Peninsula in 1999 as part of the subunit survey ranged 

from less than 1 to 22 μg/L and had a median value of 

4.5 μg/L. Water from the sampled public-supply well 

(35) on the Kenai Peninsula had a concentration of 24 

μg/L. Arsenic concentrations in water samples collected during 1999 were as great as 29 μg/L in the 

Matanuska–Susitna area and as great as 10 μg/L in 

Anchorage. The median dissolved arsenic concentrations were 2 μg/L for the subunit survey and less than 

1 μg/L for the public-supply survey.

The median barium concentrations in water from 

wells in the subunit and public-supply surveys were 9 

and 6 μg/L, respectively. Concentrations were greatest 

(106 and 133 μg/L) in water from wells 9 and 3 near 

the mouth of the Kenai River but were substantially 

below the 2,000 μg/L MCL.

Iron is dissolved from many rocks and soils and 

is an essential element in the metabolism of animals 

and plants. Iron in drinking water does not pose a 

health threat; however, on exposure to air, iron in 

water oxidizes to become a reddish-brown sediment. If 

present in excess quantities in water used for domestic 

purposes, it forms a red precipitate that stains laundry 

and plumbing fixtures, causes discoloration and 

unpleasant taste in beverages, and may promote 

growth of iron bacteria in pipes. An iron concentration 

less than 300 μg/L, the SMCL, is preferred for public 

supply. Most wells sampled yielded water having concentrations less than 10 μg/L, but water from 6 of 33 

wells had iron concentrations greater than 300 μg/L. 

The highest iron content, 18,000 μg/L, was from well 

18 in the western part of the Matanuska–Susitna area.

Having a chemistry similar to that of iron, manganese is undesirable in water supplies because in high 

concentrations it leaves black oxide stains and has an 

unpleasant taste. The SMCL for manganese is 50 

μg/L. The median dissolved manganese concentration 

was 30 μg/L for the subunit survey; 14 of the 33 wells 

sampled yielded water having manganese concentrations greater than the SMCL. The largest concentration observed was 1,460 μg/L.

PESTICIDES

Pesticides have long been used in agricultural 

settings, but their use in urban and undeveloped areas 

has increased as well. Pesticides are used in urban settings to control weeds and insects in lawns and trees; 

around homes and commercial buildings; along railroad, transmission-line, and roadway rights-of-way; 

and in private and public gardens. When present in 

drinking water or streams, many pesticides have 

adverse effects on humans and aquatic organisms. 

National water-quality standards and guidelines pertaining to pesticide contaminants were summarized by 

Nowell and Resek (1994).

Analyses of pesticides in other NAWQA subunits 

have shown that pesticide contamination in ground 

water is not just an agricultural problem; certain contaminants commonly occur in the more populated 

urban areas. Nationwide, about 50 percent of the wells 

sampled for the first 20 NAWQA study units contained one or more pesticides; the highest detection 

frequencies were in shallow ground water beneath 

agricultural and urban areas (59 and 49 percent, 

respectively), and the lowest frequencies (averaging 

33 percent) typically in deeper ground water from 

major aquifers (U.S. Geological Survey, 1999b, p. 58). 

Herbicides commonly found in shallow ground water 

were atrazine, deethylatrazine, simazine, and prometon. The most commonly detected insecticide in shallow ground water was dieldrin, which was found in 

about 3 percent of wells sampled nationwide.

In the Cook Inlet Basin, 24 percent of groundwater samples had very low concentrations of at least 

one pesticide or pesticide-degradation product (table 9 

and appendix 5). Eleven pesticides or pesticide-degradation products may have been present in water samples but at concentrations too small to be quantified. 

None of the detected pesticides had regulated MCLs 

for drinking water, but three had health advisories. The 

largest concentration detected, 0.007 μg/L, was shared 

by two compounds: methylazinphos, an insecticide 

used to control leaf-eating insects such as aphids; and 

fluometuron, an herbicide used to control weeds in 

cotton and sugarcane, crops not grown in Alaska. All 

concentrations of pesticides and pesticide-degradation 

products were far below lifetime health advisories.
22 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Table 8. Statistical summary of trace-element concentrations in water sampled from wells in Cook 

Inlet Basin, 1999

[Number in parentheses to left of constituent is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to 

identify parameter in computerized data bases. See table 2 regarding analytical methods used. MCL, maximum contaminant level; PMCL, 

proposed maximum contaminant level; SMCL, secondary maximum contaminant level. <, less than; —, none or not applicable]

Survey

network

Number of analyses Concentration

(milligrams per liter)

Criterion1

(micrograms per liter)

Total

Resulting in

concentrations

less than

minimum

reporting level

Minimum Median Maximum Drinking-water

standard

Action

level

Lifetime 

health 

advisory

(01106) Aluminum

Subunit 29 21 <1 <1 4.9 — ——

Public 5 2 <1 1 1.2 — ——

— — — — — — 50–200 (SMCL) — —

(01095) Antimony

Subunit 29 29 <1 <1 <1 — ——

Public 5 5 <1 <1 <1 — ——

(01000) Arsenic

Subunit 29 9 <1 2 29 — ——

Public 5 3 <1 <1 24 — ——

— — — — — — 50 (MCL) — —

— — — — — — 10 (PMCL) — —

(01005) Barium

Subunit 29 0 1.3 9.1 133 — ——

Public 5 0 2.8 5.8 52 — ——

— — — — — — 2,000 (MCL) —

(01010) Beryllium

Subunit 29 29 <1 <1 <1 — ——

Public 5 5 <1 <1 <1 — ——

— — — — — — 4 (MCL) — —

(01025) Cadmium

Subunit 29 29 <1 <1 <1 — ——

Public 5 5 <1 <1 <1 — ——

— — — — — — 5 (MCL) —

(01030) Chromium

Subunit 24 21 <1 <1 3 — ——

Public 5 4 <1 <1 1 — ——

— — — — — — 100 (MCL) —

(01035) Cobalt

Subunit 29 28 <1 <1 2 — ——

Public 5 5 <1 <1 <1 — ——

(01040) Copper

Subunit 29 14 <1 <1 15 — ——

Public 5 4 <1 <1 2 — ——

— — — — — — — 1,300

(01046) Iron

Subunit 29 16 <10 <10 18,000 — ——

Public 4 3 <10 <10 87 — ——

— — — — — — 300 (SMCL) —

(01049) Lead

Subunit 29 28 <1 <1 5 — ——

Public 5 5 <1 <1 <1 — ——

— — — — — — — 15
VOLATILE ORGANIC COMPOUNDS 23

VOLATILE ORGANIC COMPOUNDS

VOCs are manufactured chemicals such as 

organic solvents, byproducts of chlorinated disinfectants, and many petroleum-based derivatives that are 

components of gasoline, fuel oil, and lubricants. VOCs 

can be important environmental contaminants because 

many are mobile, persistent, and toxic. Many VOCs 

have been the focus of national regulations, monitoring, and research during the past 10 to 20 years. These 

include bromodichloromethane, chlorodibromomethane, tribromomethane, and trichloromethane, all 

of which are associated with the chlorination of drinking water; the fumigants 1,2-dibromo-3-chloropropane 

and 1,2-dibromomethane (commonly referred to as 

DBCP and EDB, respectively); the solvents tetrachloroethylene and trichloroethene (PCE and TCE, respectively); and the gasoline aromatic hydrocarbons 

(commonly referred to as BTEX compounds) benzene, 

toluene (methyl benzene), ethyl benzene, and xylenes 

(dimethylbenzenes). The gasoline additive used to 

reduce carbon monoxide emissions from vehicles during winter, methyl tert-butyl ether (MTBE), also has 

received much attention in recent years and commonly 

has been found in shallow aquifers beneath urban 

areas. Rowe and others (1997) and Bender and others 

(1999) described human-health criteria, drinkingwater regulations, aquatic-toxicity criteria, and other 

information for many of the VOCs analyzed for this 

study.

1

U.S. Environmental Protection Agency (2000).

Table 8. Statistical summary of trace-element concentrations in water sampled from wells in Cook 

Inlet Basin, 1999—Continued

Survey

network

Number of analyses Concentration

(milligrams per liter)

Criterion1

(micrograms per liter)

Total

Resulting in

concentrations

less than

minimum

reporting level

Minimum Median Maximum Drinking-water

standard

Action

level

Lifetime 

health 

advisory

(01056) Manganese

Subunit 29 12 <1 30 1,460 — ——

Public 5 4 <1 <1 38 — ——

— — — — — — 50 (SMCL) — —

(01065) Nickel

Subunit 29 17 <1 <1 1.9 — ——

Public 5 4 <1 <1 1.8 — ——

— — — — — — — — 100

(01145) Selenium

Subunit 29 28 <1 <1 1 — ——

Public 5 4 <1 <1 1 — ——

— — — — — — 50 (MCL) — —

(01075) Silver

Subunit 29 29 <1 <1 <1 — ——

Public 5 5 <1 <1 <1 — ——

— — — — — — 100 (SMCL) — —

(22703) Uranium

Subunit 29 29 <1 <1 <1 — ——

Public 5 5 <1 <1 <1 — ——

— — — — — — 20 (MCL) — —

(01090) Zinc

Subunit 29 1 <1 12 76 — ——

Public 5 1 <1 1.3 2.1 — ——

— — — — — — 5,000 (SMCL) — —
24 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Nationwide, the frequency of detection of VOCs 

in ground water is greater in urban areas than in rural 

areas having fewer than 1,000 people per square mile; 

nearly 50 percent of wells sampled in urban areas had 

at least one VOC detected (minimum reporting level, 

0.2 μg/L) compared with about 14 percent of wells 

sampled in rural areas (Squillace and others, 1999). 

Drinking-water criteria for at least one VOC were 

exceeded in water samples from 6.4 percent of all 

sampled wells in urban areas nationwide and 2.5 percent of urban wells used as sources of drinking water. 

The most commonly detected VOCs in urban areas 

were trichloromethane (detected in 26 percent of 

urban wells sampled), MTBE (in 17 percent), PCE (in 

17 percent), and TCE (in 12 percent). Because their 

occurrence is widespread, these four VOCs commonly 

occur together although they are not necessarily used 

together. MTBE is used in gasoline, and the remaining 

three VOCs are classified as solvents. However, trichloromethane can form during chlorination of drinking-water supplies, and lawn irrigation or the leaking 

of water mains and sewers can introduce this VOC to 

urban ground water. That tetrachloroethylene can 

degrade into trichloroethene may explain in part why 

these two VOCs occur together.

More than 80 VOCs were analyzed for this study, 

but only 9 compounds were detected (table 10 and 

appendix 6). All concentrations were less than 1 μg/L 

and were below MCLs for drinking water. Toluene 

was detected in 22 of 33 ground-water samples at concentrations as great as 0.77 μg/L. However, toluene 

also was detected in the quality-control samples; thus, 

the concentrations and frequency of detection of

toluene in environmental samples likely are overestimated. The presence of toluene in quality-control 

and ground-water samples may be due to the use of 

contaminated field or laboratory equipment or the analytical method used. The compound 1,2,4-trimethylbenzene was detected in 10 of 33 ground-water samples at concentrations as great as 0.17 μg/L. TrichloTable 9. Pesticides detected in water sampled from wells in Cook Inlet Basin, 1999

[See table 2 regarding analytical methods used. Well number: See table 1 and fig. 2. —, none]

1

Estimated values.

2

For 70-kilogram (154-pound) adult (U.S. Environmental Protection Agency, 2000).

Constituent Alternative term

or trade name

Number of

samples

analyzed

Number of

detections

Well

number

Method

detection limit

(micrograms

per liter)

Maximum

concentration1

(micrograms

per liter)

Lifetime

health

advisory2

(micrograms

per liter)

Deethylatrazine DEA 33 1 11 0.002 0.0015 —

Methyl azinphos Guthion or Carfene 33 1 5 .001 .007 —

p,p-DDE p,p-DDT metabolite 33 3 4, 24, and 31 .006 .002 —

Propanil — 33 1 11 .004 .002 —

Tebuthiuron Spike or Perflan 33 1 11 .01 .004 500

Carbofuran — 33 1 24 .057 .0008 40

3-Hydroxy-carbofuran — 33 1 24 .062 .0013 —

Diuron — 33 2 15 and 31 .079 .002 10

Fluometuron — 33 1 14 .062 .007 90

Metsulfuron methyl — 33 1 24 .114 .002 —

Neburon — 33 2 22 and 24 .075 .0011 —
ENVIRONMENTAL ISOTOPES 25

rofluoromethane (CFC-11 or freon-11), a refrigerant, 

was detected in 9 of 33 ground-water samples at concentrations as great as 0.84 μg/L. CFCs also were collected by using a sampling apparatus that allowed 

water collection without contact with air and were 

analyzed by a technique that allows detection at much 

lower concentrations. The substantially lower concentrations of trichlorofluoromethane determined by this 

technique suggest that the regular samples were contaminated by atmospheric sources of CFCs or that the 

field or laboratory equipment was contaminated.

The highest trichlorofluoromethane concentration 

observed by using the lower-detection analytical procedure was 20,000 pg/kg (approximately 0.02 μg/L). 

Results of CFC analyses are discussed in the section 

“Age Dating of Ground-Water Recharge.”

When toluene is excluded, water from 15 of 33 

(or 45 percent of) wells sampled for organic constituents had at least one VOC detected, and 5 of those 

wells (5, 14, 15, 22, and 24) had at least one pesticide 

and at least one VOC detected. Water samples from 16 

of the 32 wells that were sampled for both pesticides 

and VOCs had no pesticide or VOC detected.

ENVIRONMENTAL ISOTOPES

Isotopes are atoms of the same element that differ 

in mass because of a difference in the number of neutrons in their nuclei. The naturally occurring elements 

give rise to more than 1,000 radioactive and stable isotopes, commonly referred to as “environmental isotopes.” 

Radioactive Isotopes

Radioactivity is the property possessed by some 

elements (such as uranium and thorium) or isotopes 

(such as carbon-14) of spontaneously emitting energetic particles by the disintegration of their atomic 

nuclei. Water samples were analyzed for the general 

presence of radioactivity by techniques used to determine gross-alpha and gross-beta emissions (table 11 

and appendix 7). Also determined were the activity 

concentrations of several specific radiochemical constituents, including radon-222 and radium-224, -226, 

and -228. Tritium, a radioactive isotope of hydrogen

1U.S. Environmental Protection Agency (2000).

2Also detected in two field blanks and one trip blank.

3

Detected in both environmental sample and associated blanks.

4

Estimated values.

Table 10. Volatile organic compounds detected in water sampled from wells in Cook Inlet Basin, 1999

[See table 2 regarding analytical methods used. Well number: See table 1 and fig. 2. MCL, maximum contaminant level; —, none or not applicable]

Constituent Number of

analyses

Number of

detections

Well

number

Method

detection limit

(micrograms

per liter)

Maximum

detected

(micrograms

per liter)

Criterion1

(micrograms per liter)

Drinking-water

standard

Lifetime

health

advisory

Toluene 33 2

22 1, 2, 4, 5, 6, 7, 8, 9, 10, 14, 

15, 16, 20, 22, 24, 25, 26, 

27, 29, 30, 34, and 35

0.05 30.77 1,000

(MCL)

—

1,2,4-Trimethylbenzene 33 10 1, 5, 14, 15, 16, 22, 25, 26, 

27, and 30

.056 .17 — —

Trichlorofluoromethane 33 9 1, 5, 7, 14, 16, 25, 26, 28, 

and 30

.09 .84 — 2,000

Chloroform 33 2 15 and 32 .052 4.023 80

(MCL)

—

1,1,1-Trichloroethane 33 2 10 and 24 .032 4

.031 200

(MCL)

—

M- and p-Xylene 33 2 5 and 30 .06 4.041 10,000

(MCL)

—

Carbon disulfide 33 1 18 .37 4.05 — —

Chlorobenzene 33 1 16 .028 4.007 — —

Tetrachloroethylene 33 1 14 .1 4.047 5

(MCL)

—
26 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

1U.S. Environmental Protection Agency (2000).

Table 11. Statistical summary of radioisotopes, environmental isotopes, and chlorofluorocarbon concentrations in water sampled from wells in Cook Inlet Basin, 1999

[Number in parentheses to left of constituent is number used by both U.S. Environmental Protection Agency and

U.S. Geological Survey to identify parameter in computerized data bases. See table 2 regarding analytical methods 

used. CFC, chlorofluorocarbon; MCL, maximum contaminant level; PMCL, proposed maximum contaminant level; 

VSMOW, Vienna Standard Mean Ocean Water. <, less than; —, not detected, no criteria (or no separate criteria), or 

not applicable]

Survey

network

Number of

analyses

Concentration Drinking-water

standard1 Minimum Median Maximum

Radioactivity (picocuries per liter)

(04126) Alpha radioactivity as thorium-230, dissolved:

Subunit 29 <3 <3 5.4 —

Public supply 5 <3 <3 <3 —

— — — — — 15 (MCL)

(03515) Beta radioactivity as cesium-137, dissolved:

Subunit 29 <4 <4 10 —

Public supply 5 <4 <4 4.8 —

Radium (picocuries per liter)

(50833) Radium-224, dissolved:

Subunit 29 <1 <1 <1 —

Public supply 5 <1 <1 <1 —

(09503) Radium-226, dissolved:

Subunit 29 <1 <1 <1 —

Public supply 5 <1 <1 <1 —

(81366) Radium-228, dissolved:

Subunit 28 <1 <1 <1 —

Public supply 5 <1 <1 <1 —

(09053; 81366) Radium-226 and -228, dissolved (combined):

— — —— — 5 (MCL)

Radon (picocuries per liter)

(82383) Radon-222, total:

Subunit 26 140 260 610 —

Public supply 5 140 240 580 —

— — —— — 300 (PMCL)

Hydrogen and oxygen isotope ratios (per mil relative to VSMOW)

(82082) Hydrogen-2/hydrogen-1 ratio:

Subunit 25 -164 -130 -89 —

Public supply 4 -162 -136 -126 —

(82085) Oxygen-18/oxygen-16 ratio:

Subunit 25 -21.3 -16.5 -9.1 —

Public supply 5 -21.1 -17.6 -16 —

Chlorofluorocarbons (picograms per kilogram)

(50281) CFC-11:

Subunit 25 — 20 20,000 —

Public supply 5 — 20 2,000 —

(50282) CFC-12:

Subunit 25 1 100 3,000 —

Public supply 4 — 60 500 —

(50283) CFC-113:

Subunit 25 — 5 90 —

Public supply 5 — 3 100 —
ENVIRONMENTAL ISOTOPES 27

that has been added to the atmosphere by the detonation of nuclear bombs, also was analyzed to help determine the apparent age of ground-water samples and is 

discussed in the section “Age Dating of Ground-Water 

Recharge.”

Gross-alpha and gross-beta activities of dried residues of water samples and radionuclides of radon and 

radium are reported in radioactivity units (picocuries 

per liter), as thorium-230 and cesium-137, respectively. Such measurements of particle activities and 

analyses of radionuclides are preliminary screening 

procedures for the presence of radioactivity but do not 

identify the contributing radionuclides. Most grossalpha and gross-beta particle activities observed were 

below their laboratory detection levels, 3 and 4 pCi/L, 

respectively (table 11 and appendix 7). The highest 

gross-alpha activity observed was 5.4 pCi/L as thorium-230, and the highest gross-beta particle activity 

observed was 10 pCi/L as cesium-137. The MCL for 

gross-alpha particle activity is 15 pCi/L. The MCL for 

gross-beta radioactivity is an effective dose equivalent 

to 4 millirem per year.

Alpha-emitting substances in natural water are 

mainly isotopes of radium and radon. Four isotopes of 

radium (radium-223, -224, -226, and -228) occur naturally and are all strongly radioactive. Radium is chemically similar to calcium and collects in bone tissue 

where it can induce bone cancers. The current drinking-water standard established for radium (radium-226 

and radium-228 combined) is 5 pCi/L (U.S. Environmental Protection Agency, 2000). The concentration 

of radium in most natural waters is typically less than 

1 pCi/L. All water samples from wells in the Cook 

Inlet Basin had radium-224, -226, and -228 activities 

less than the method detection limit of 1 pCi/L (table 

11 and appendix 7).

Radon-222 is a naturally occurring radioactive 

gas that is produced by the decay of uranium. Rocks 

and sediments commonly contain high enough concentrations of uranium to cause ground water to have 

significant concentrations of radon. Radon is soluble in water but readily degasses from water when 

exposed to air. It may be adsorbed by organic matter, 

especially charcoal, but apparently it is not adsorbed to 

any degree by most minerals (Wanty and Nordstrom, 

1993). Radon has a short half-life, 3.8 days, but large 

quantities can occur in the gas phase below the land 

surface. Direct ingestion of radon from drinking water 

appears not to be a serious health risk. Radon poses a 

more serious risk in indoor air; in water supplies, it 

quickly degasses when the water comes into contact 

with the atmosphere. The health risk of airborne radon 

arises from inhalation of radon and its alpha-emitting 

daughters, all of which may deposit on lung tissue and 

can lead to lung cancer. Radon was present in all water 

sampled from wells in the Cook Inlet Basin at activities ranging from 140 to 610 pCi/L. As of this writing, 

the USEPA does not regulate radon in drinking water. 

However, activities exceeded the proposed MCL of 

300 pCi/L in 12 of 31 water samples. The national 

median radon activities from the first 20 NAWQA 

study units were 450 pCi/L for drinking-water aquifers 

and 470 pCi/L for shallow ground water (Gilliom and 

others, 1998, p. 19).

Uranium is present in concentrations of 0.1 to

10 μg/L in most natural water (Hem, 1985). When 

ingested, uranium may cause kidney damage or induce 

bone cancer. The MCL for uranium is 20 μg/L. All 

samples of ground water from the Cook Inlet Basin 

that were analyzed for uranium in this study had concentrations less than the method detection limit, 1 

μg/L (table 8 and appendix 4).

Stable Isotopes of Hydrogen and Oxygen 

The variation in the abundance of the stable isotopes of hydrogen, carbon, nitrogen, oxygen, silicon, 

and sulfur in natural substances is small. Determining 

the differences in the relative ratios of a less abundant 

isotope to its more abundant isotope in ground- and 

surface-water samples can help provide information 

on the source of the water, the interactions between 

surface and ground water, and the hydraulic properties 

of an aquifer. For this study, ratios of the stable isotopes of hydrogen and oxygen were determined to 

help characterize water in the aquifer.

Hydrogen is most commonly present as hydrogen-1 (1

H) but is also present as deuterium (2H) and 

tritium (3

H). Tritium is a radioactive isotope and is 

discussed in the section “Age Dating of Ground-Water 
28 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Recharge.” Oxygen most commonly is in the form 

oxygen-16 (16O) but is also naturally present in the 

form oxygen-18 (18O). Analytical results for the isotopes of hydrogen and oxygen (table 11 and appendix 

8) are reported relative to a standard as delta (δ) values 

in units of parts per thousand (per mil). The δ notation 

expresses the parts-per-thousand difference in the ratio 

of the heavier less abundant isotope to the more abundant isotope in a sample relative to the same ratio in a 

reference standard:

where Rsample is the isotopic ratio 2H/1H or 18O/16O 

in the sample and Rstandard is the isotopic ratio 2H/1H 

or 18O/16O in Vienna Standard Mean Ocean Water 

(VSMOW) (Freeze and Cherry, 1979, p. 137). A negative δ value indicates that the sample is depleted in the 

heavy isotope relative to the standard. Modern ocean 

water at low latitudes commonly has δ2H and δ18O 

values close to 0, relative to VSMOW. When water 

evaporates, the water vapor produced is depleted in the 

heavy isotopes 2

H and 18O. The water vapor progressively is depleted in 2

H and 18O as an air mass moves 

to higher latitudes and its temperature decreases, 

thereby causing the heavier isotopes to be precipitated preferentially. When the water vapor falls to the 

ground as precipitation and percolates through the 

unsaturated zone, its isotopic ratios change little. 

However, evaporation of water in lakes and streams 

enriches 2

H and 18O in the remaining water, and the 

water vapor is further depleted in 2H and 18O. Globally, the relation between δ2H and δ18O in meteoric 

water (water of recent atmospheric origin) approximates δ2H = 8 δ18O + 10, but in North America, the 

relation approximates δ2H = 8 δ18O + 6.

All wells in the Cook Inlet Basin yielded water 

that had δ2H and δ18O values below the meteoric relation (fig. 4), as was expected because of the study 

area’s high latitude and the low temperature of its precipitation. Best-fit lines of the measured data show a 

divergence from VSMOW, indicating possible evaporation of some of the water before recharge. The lowest isotopic values (δ2

H and δ18O values less than

-150 and less than -20 per mil relative to VSMOW, 

respectively) were from wells 24, 26, and 31 in the 

eastern Matanuska–Susitna area. Such values indicate 

that the sources of water recharge for these wells may 

have been more mountainous, cooler, more northern, 

or farther inland than other water sources or that the 

water had been deposited in glaciers during different 

climatic conditions. The Matanuska River may be a 

large source of recharge for these wells. About 12 percent of the 2,070-mi2

 drainage area for the Matanuska 

River is covered by glaciers. Water from wells 2 and 

15 had the highest δ18O and δ2

H values, indicating the 

samples were least depleted in heavy isotopes relative 

to VSMOW. Some of the ground-water recharge to 

these two wells may have been from lakes or wetlands 

containing water enriched in deuterium and oxygen-18 

by evaporation.

AGE DATING OF GROUND-WATER 

RECHARGE

Tritium and CFCs are two substances that have 

been added in large quantities to the atmosphere by 

man within the last 50 years. In the atmosphere, tritium and CFCs dissolve in water and fall to the Earth’s 

surface in precipitation. Water infiltrating the ground 

contains these substances, and they are transported 

through aquifers at the same rate as ground water. The 

presence of tritium and CFCs in ground water can help 

determine the time elapsed since the water became 

isolated from the atmosphere, help infer flow velocity 

and direction, and help predict contamination potential 

(Plummer and Friedman, 1999). Most of the urban, 

commercial, and residential development in the Cook 

Inlet Basin has occurred within the last 50 years. 

Because the usage and distribution of petroleum products, fertilizers, pesticides, and septic-tank effluents 

were minimal more than 50 years ago and because 

many organic contaminants break down to other compounds over time in the natural environment, few 

organic contaminants are expected to be present in 

local waters that were recharged more than 50 years 

ago. However, wells that yield recently recharged 

water have water supplies that are susceptible to 

anthropogenic contaminants.

δsample

(Rsample Rstandard – )

Rstandard

= -------------------------------------------------------------- × 1000
AGE DATING OF GROUND-WATER RECHARGE 29

Tritium

Tritium (3

H) is a radioactive isotope of hydrogen 

that has a half-life of about 12.4 years, is produced 

naturally, and decays to the stable isotope helium-3 

(

3

He). Prior to the initiation of atmospheric testing of 

nuclear weapons in 1953, the natural tritium content in 

precipitation was in the range of about 5 to 20 tritium 

units (TU) (Freeze and Cherry, 1979, p. 136). (A tritium unit is the equivalent of 1 tritium atom in 1018

atoms of hydrogen or an activity of 3.24 pCi/L.) During the last 50 years, the atmospheric testing of nuclear 

weapons has added tritium in amounts that far exceed 

the rate of natural production. Explosions of nuclear 

devices produced a maximum mean annual tritium 

concentration in precipitation during 1963–64 (about 

8,000 TU in some parts on the northern hemisphere). 

Concentrations in precipitation in Anchorage (measured in monthly composite samples) had decreased

to less than 100 TU as of 1975 and ranged from 4

to 17 TU during 1999 (International Atomic Energy 

Agency/World Meteorological Organization, 2001). 

Stewart and Hoffman (1966) estimated that the 

weighted-average tritium rainout concentration for 

Palmer, Alaska, had been 2,950 TU during 1963, 

which would have decayed to about one-eighth of this 

activity by 1999. Water recharged after 1963 may contain tritium at activity concentrations of 2 to 400 TU. 

Figure 4. Isotope ratios of deuterium and oxygen-18 for water sampled from wells in Cook Inlet Basin, 1999.

Matanuska−Susitna Borough

Kenai Pennisula Borough

Municipality of Anchorage

-22 -21 -20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0

OXYGEN-18, IN PER MIL RELATIVE TO VIENNA STANDARD MEAN OCEAN WATER

-170

10

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

DEUTERIUM, IN PER MIL RELATIVE TO VIENNA STANDARD OCEAN WATER

Global meteoric water line: Deuterium = 8(oxygen-18) + 10

Cook Inlet Basin ground water: Deuterium = 6.2(oxygen-18) − 27.6

Subunit survey

Public-supply survey

R2 = 0.96

Matanuska−Susitna Borough

Kenai Pennisula Borough

Municipality of Anchorage
30 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Water samples containing no detectable concentrations 

of tritium may indicate that post-1953 water is not 

present in significant amounts.

Measured tritium activities in ground water samples from Cook Inlet Basin during 1999 ranged from 

less than 1 to 35 TU and had a median value of 12

TU. Apparent ground-water ages (age since recharge) 

listed in appendix 9 were estimated by personnel from 

the Lamont–Doherty Earth Observatory (Peter Schlosser and others, written commun., 2000) by simultaneously using activities of tritium and its decay product, 

helium-3. This technique, described by Schlosser 

(1992) and Busenberg and Plummer (1992), allows a 

more accurate estimate of time elapsed since recharge 

because, together, tritium and helium-3 permit reconstruction of the initial tritium concentration before 

radioactive decay begins. The upper and lower estimates of ground-water recharge ages based on the tritium–helium content in the first sample analyzed for 

each site (recharge age ± precision estimate) are 

shown in figure 5. Apparent ages were estimated to 

range from less than 1 to greater than 50 years, and 

median ages, approximately 19 and 16 years for water 

from the subunit and public-supply surveys, respectively. However, wells yielding water having low tritium concentrations are difficult to date accurately and 

thus have wide ranges in their apparent ages. Of 31 

wells, 8 yielded water that may have been recharged 

within the last than 10 years, and only 3 (wells 6, 16, 

and 35) yielded water that may have been recharged 

greater than 50 years ago and thus before nuclear testing, on the basis of their tritium activities.

Chlorofluorocarbons

CFCs are a group of stable manmade compounds 

containing chlorine and fluorine that have been used in 

numerous domestic and industrial applications since 

the 1930s and do not occur naturally in the environment. Atmospheric CFCs dissolve in precipitation and 

enter the ground-water flow systems with recharge; 

thus, like tritium, they provide excellent tracers and 

tools for dating “young” water. Because CFCs do not 

occur naturally in the environment, ground water containing any amount of CFC must have a component of 

modern recharge water.

CFCs were used as coolants in air conditioning; 

as propellants in aerosol cans; as blowing agents for 

open- and closed-cell foams, insulation, and packing 

materials; and as solvents. However, the manufacturing of most CFC products ended in 1996 because of 

concerns about CFCs depleting ozone in the stratosphere. For this study, three types of CFCs were analyzed: CFC-11 (trichlorofluoromethane or freon-11), 

CFC-12 (dichlorodifluoromethane), and CFC-113 

(1,1,2-trichlorotrifluoroethane). CFC-11 and CFC-12 

are gases at ordinary temperatures that normally volatilize when released and accumulate in the atmossphere, whereas CFC-113 is a liquid at ordinary temperatures.

Concentrations of CFCs are measured in the air 

at Barrow, Alaska, by the National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory. During 1999, atmospheric concentrations of CFC-11, CFC-12, and CFC-13 were 263–

267, 533–537, and 81–83 parts per trillion by volume, 

respectively (National Oceanic and Atmospheric 

Administration, 2001). However, CFC concentrations 

in the COOK study unit may have been greater than 

the concentrations at Barrow because Cook Inlet Basin 

is much more populated and hence the total amount of 

CFC used in the basin is much greater than that used

in Barrow. Even though the concentration of CFC-12 

was nearly twice that of CFC-11, the solubilities in 

water are reversed. The solubility of CFC-11 in water 

in equilibrium with 1999 atmosphere is approximately 

1,300 pg/kg, compared with about 520 pg/kg for CFC12 (calculated assuming a recharge temperature of 

2°C).

Relative ages of ground-water recharge can be 

determined by using the known solubilities of CFCs

in water and historical data on the concentrations of 

CFCs in the atmosphere (Busenberg and Plummer, 

1992; Plummer and Busenberg, 1999). For this study, 

concentrations of CFCs were determined by techniques that allow detection at extremely low levels, 

about 0.3 pg/kg (equivalent to 3 x 10-13 g/kg, or 0.3 

parts per quadrillion). For water recharged through relatively thin unsaturated zones, concentrations near the 

detection limit for CFC-11, CFC-12, and CFC-113 

indicate ground-water recharge since approximately 

1941, 1947, and 1955, respectively, or ground-water 

mixtures containing a fraction of post-1940s water. If 

CFCs are present in a ground-water sample, the water 

is considered to be “modern”; if a concentration in the 

sample is greater than that possible for equilibrium 

with the air, the sample is referred to as “contaminated.”
A

GEDATINGOFGROUND-WATERRECHARGE31Figure 5. Dates of recharge determined by using chlorofluorocarbon and tritium analyses of water from wells in Cook Inlet Basin, 1999.

1 2 3 4 56789 10 11 12 13 14 15 16 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

WELL NUMBER

YEAR OF RECHARGE

20102000

1990

1980

1970

1960

1950

1940

EXPLANATION

CFC

CFC

CFC

Chlorofluorocarbons:

Tritium

11

12

113

No tritium analyses or chlorofluorocarbons

No tritium analyses or chlorofluorocarbons

No tritium analyses or chlorofluorocarbons

No chlorofluorocarbons 

No tritium analyses
32 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

However, several processes can affect CFC

concentrations and estimations of apparent age 

(Busenberg and Plummer, 1992; Plummer and Busenberg, 1999). Peat and other organic materials present 

throughout the study unit can adsorb CFCs; the resulting decrease in amounts that reach the used parts

of the aquifers produces an older apparent age for 

recharge. Microbes can also degrade CFCs when the 

water in the aquifer contains little dissolved oxygen. In 

anoxic environments, CFC-11 degrades at the fastest 

rate, succeeded by CFC-113 and then by CFC-12. 

Under anoxic conditions, some or all the ages appear 

older than they actually are. CFCs also are degraded 

by methane. Effluent from domestic septic tanks may 

contain CFCs and increase CFC concentrations in 

recharge water and make the water appear younger. 

Because CFCs are present in the air, a special sampling apparatus that prevents contact of the water sample with air was used. A borosilicate ampule was 

flushed with ultrapure nitrogen gas and then with well 

water; then the ampule was flame sealed, thereby leaving a nitrogen-filled head space.

Five ampules were filled at most sites; typically 

water from three were analyzed by personnel from the 

USGS Chlorofluorocarbon Laboratory in Reston, Va. 

(G.C. Casile, written commun., 2000) to determine 

concentrations of CFC-11, CFC-12, and CFC-113 and 

apparent ages. Apparent ages based on the concentrations of CFCs in water from each ampule analyzed are 

shown in figure 5; values for the average CFC concentrations for each site are listed in appendix 10 and are 

stored in the USGS National Water Information System data base. Almost all wells yielded water containing detectable concentrations of CFCs. Water from 

well 35 had no detectable CFCs but was anoxic and 

chemically reduced. CFC concentrations in water samples that are greater than possible for equilibrium with 

modern air are referred to as “contaminated” (see 

appendix 10) and were not used to determine apparent 

age. By this definition, ground water from urban areas 

commonly is “contaminated” with CFCs; a likely 

source of CFC contamination is effluent from domestic septic tanks. However, all CFC concentrations 

detected were less than 0.1 μg/L and present no risk to 

human health. Apparent ages based on concentrations 

of the three types of CFCs analyzed ranged from 7

to greater than 50 years old, and the median age was 

about 34 years old.

Of 31 sites sampled to determine age of recharge, 

29 had both CFC and tritium analyses. Of 29 samples, 

24 had tritium-based apparent ages that were younger 

than their CFC-based ages. Differences in ages for 

water samples from the same well ranged from a CFCbased age that was about 15 years younger than the tritium-based age to a CFC-based age that was about 30 

years older than the tritium-based age; the standard 

deviation between paired CFC- and tritium-based ages 

was 11 years. These differences suggest that CFCs 

were not as conservative as tritium in the Cook Inlet 

aquifer system’s hydrogeologic environment. CFC-12, 

the most conservative of the three CFCs, yielded ages 

closest to the tritium-based ages (fig. 5). CFC-11 and 

CFC-113 analyses may overestimate ground-water age 

owing to their greater absorption by peat, degradation 

by microbes, or reduction during sampling. Typically, 

CFC-11 is more susceptible to degradation and therefore the computed ages of recharge based on CFC-11 

are most likely older than actual recharge. Accordingly, if CFC-11 ages are considered maximum ages, 

most wells sampled yielded water that was recharged 

less than 50 years ago.

SUMMARY

A regional assessment of ground-water quality in 

the Cook Inlet Basin in south-central Alaska during 

1999 was based on analyses of water collected from 

34 wells. Water from several wells screened in the 

unconsolidated aquifers in Cook Inlet Basin contained 

concentrations of radon and arsenic that exceeded

proposed drinking-water standards. Of the 34 wells 

sampled, 39 percent yielded water having radon concentrations in excess of the USEPA proposed MCL

of 300 pCi/L, and 18 percent had dissolved arsenic 

concentrations that exceeded the proposed MCL of

10 μg/L. The highest concentrations of radon and 

arsenic measured during this study were 610 pCi/L 

and 29 μg/L, respectively. Concentrations greater than 

proposed standards for both radon and arsenic were 

observed in ground water in the Kenai, Anchorage, 

and Matanuska–Susitna areas. Concentrations of manganese, iron, and dissolved solids exceeded USEPA 

SMCLs in water from 42, 18, and 6 percent of wells 

sampled, respectively. Concentrations of arsenic, 

radon, manganese, iron, and dissolved solids are 

related to the geologic materials that make up the aquifers and the chemical conditions within the aquifers. 
REFERENCES CITED 33

Most wells that yielded water having elevated concentrations of arsenic also yielded water having elevated 

iron and manganese content but had low concentrations of oxygen, indicating chemically reduced conditions.

Ground-water samples collected in the Anchorage and Matanuska–Susitna areas typically had calcium as the dominant cation and bicarbonate as the 

dominant anion. Water near the Matanuska River had 

higher proportions of sulfate than water in other areas. 

Water from wells on the Kenai Peninsula typically had 

the highest proportions of sodium, chloride, and silica. 

Wells completed in a confined aquifer near the mouth 

of the Kenai River yielded water having the highest 

concentrations of dissolved solids, sodium, chloride, 

and barium. Concentrations of nitrate were highest in 

Anchorage and were as large as 4.8 mg/L as N; none 

exceeded the MCL of 10 mg/L as N. The presence of 

nitrate in water at concentrations above 3 mg/L in the 

eastern part of Anchorage may indicate some effects 

of human activities on the water quality.

Half of the wells sampled for both pesticides and 

VOCs had no detectable pesticides or VOCs. Of 11 

pesticide compounds detected at very low concentrations, the largest concentration was estimated to be 

0.007 μg/L. Nine VOCs were detected, all at concentrations of less than 1 μg/L. No pesticides or VOCs 

were detected at concentrations exceeding MCLs or 

health advisories. These low values for concentrations 

of pesticides and VOCs in ground water throughout 

the study unit indicate no widespread contamination of 

ground water.

Concentrations of hydrogen and oxygen isotopes 

in ground-water samples were similar to concentrations expected for modern precipitation and for water 

that has been affected by evaporation before infiltration. Water samples from most wells in the Cook Inlet 

Basin yielded values for tritium activities and CFC 

concentrations that support recharge ages of less than 

50 years. Because ages based on tritium activities generally were younger than those based on CFC concentrations, CFCs may have been absorbed by organic 

materials in soils or aquifer materials or degraded by 

microbes.

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APPENDIXES
APPENDIXES 39

1Estimated values

Appendix 1. Physical properties and field measurements for water sampled from wells in Cook Inlet Basin,1999

[Well number: See table 1 and fig. 2. Number in parentheses above property or constituent is number used by both U.S. Environmental Protection Agency and U.S. Geological 

Survey to identify parameter in computerized data bases. <, less than; > greater than]

Well

number

Date of

sample

collection

(72004)

Duration of

pumpage

prior to sampling

(minutes)

(00059)

Flow rate

 (gallons

per

minute)

(00010)

Water

temperature

(degrees

Celsius)

(00400)

pH

(standard

units)

(00300)

Dissolved

oxygen

(milligrams

per liter)

(00095)

Specific

conductance

(microsiemens

per centimeter)

(39086)

Alkalinity

(milligrams

per liter

as CaCO3)

Subunit survey

1 08/27/99 60 5 3.5 7.0 0.3 130 58

2 08/10/99 30 8 5.0 7.3 .2 77 45

3 08/27/99 30 10 5.0 8.3 .1 1,750 384

4 09/01/99 60 1

30 4.0 6.7 6.0 84 34

5 09/21/99 60 5 6.5 6.7 .2 415 92

6 07/28/99 60 10 3.5 8.0 .1 265 150

7 08/03/99 60 5 5.0 8.1 7.6 230 111

8 08/03/99 45 5 4.0 7.7 9.4 298 173

9 08/11/99 90 5 9.5 8.0 .2 946 146

10 08/09/99 60 8 4.0 7.0 2.4 146 55

11 08/10/99 60 5 4.5 7.2 .2 118 66

12 07/27/99 105 1

5 3.0 7.7 .1 280 142

13 07/26/99 60 500 3.5 8.0 .4 290 143

14 08/04/99 30 45 5.0 7.7 .2 401 207

15 08/06/99 60 7 8.5 6.9 1.2 117 63

16 09/13/99 60 6 4.0 8.0 .1 164 91

18 08/06/99 40 5 4.5 6.9 .1 180 97

19 08/04/99 30 8 4.5 8.2 4.6 263 128

20 08/02/99 90 10 5.5 7.8 9.6 307 151

21 07/30/99 >300,000 725 4.5 7.9 5.5 210 97

22 08/25/99 90 5 3.5 8.2 11.0 240 128

23 07/27/99 90 15 5.5 8.2 1.9 255 91

24 09/29/99 60 5 4.0 7.4 9.0 450 165

25 09/15/99 30 5 3.5 8.0 8.0 225 113

26 08/31/99 30 5 4.5 7.9 11.8 300 88

27 08/30/99 35 5 4.0 7.9 7.0 260 130

28 08/16/99 60 5 4.0 8.0 .2 237 129

29 08/23/99 75 6 4.0 7.7 .6 270 145

30 10/20/99 75 10 4.0 8.3 .5 250 127

Public-supply survey

31 08/24/99 30 1,200 4.0 7.6 11.0 310 100

32 07/26/99 90 1,400 4.0 8.0 1 209 103

33 07/21/99 210 1,800 2.5 8.4 1.6 177 90

34 07/23/99 200 1,200 4.0 7.1 9.4 168 77

35 08/11/99 >90 650 5.0 8.1 <.1 201 100
40 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Appendix 2. Concentrations of major ions in water sampled from wells in Cook Inlet Basin,1999

[Well number: See table 1 and fig. 2. Number in parentheses above constituent is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey 

to identify parameter in computerized data bases. Highlighted values exceed a water-quality standard. National median concentrations for drinking-water aquifers are 

from Gilliom and others (1998). <, less than; —, not analyzed, unknown, or not applicable]

Well

number

Concentration

(milligrams per liter)

(00915)

Calcium

(00925)

Magnesium

(00930)

Sodium

(00935)

Potassium

(00453)

Bicarbonate,

as HCO3

(00945)

Sulfate

(00940)

Chloride

(00950)

Fluoride

(71870)

Bromide

(00955)

Silica

(70300)

Dissolved

solids,

residue

at 180oC

Subunit survey

1 12 6.0 5.7 3.2 71 2.1 4.3 <.1 0.02 34 104

2 7.9 3.7 4.9 1.8 55 .16 3.3 <.1 .01 37 83

3 4.4 5.0 360 9.9 468 <.1 500 <.1 .87 44 986

4 11 2.1 3.6 1.1 42 1 6.1 <.1 <.01 29 77

5 40 11 15 3.5 113 3.2 77 <.1 .05 31 268

6 38 8.7 11 2.2 182 <.1 1.1 <.1 <.01 15 169

7 45 2.9 2.0 .52 135 <.1 2.1 <.1 <.01 12 145

8 52 6.5 6.5 .87 211 <.1 1.1 <.1 .02 14 180

9 25 18 127 13 178 .33 210 .12 .36 44 549

10 14 6.4 5.0 1.9 66 1.3 12 <.1 .03 26 99

11 14 5.6 5.2 2.2 81 1.7 3.5 <.1 .06 30 96

12 44 8.7 3.5 1.4 173 8.7 2.9 <.1 .02 26 184

13 41 13 4.2 1.2 174 7.3 4.0 <.1 <.01 15 163

14 72 9.4 3.6 .95 253 2.7 5.0 <.1 .04 18 218

15 19 3.4 2.6 .25 77 1.5 2.0 <.1 <.01 8.4 85

16 22 5.5 4.8 .79 111 2 1.3 .15 <.01 15 102

18 23 5.8 3.4 .91 118 .88 17 <.1 <.01 26 154

19 47 5.5 3.1 .93 156 8.8 2.8 <.1 .02 10 163

20 55 7.1 2.1 2.9 184 9.9 3.4 <.1 .02 12 184

21 36 6.1 2.4 .49 118 19 1.5 <.1 <.01 11 138

22 48 8.5 3.2 .55 156 12 4.9 <.1 .01 12 172

23 32 12 2.7 .84 111 11 10 <.1 .03 12 164

24 77 9.2 7.6 1.0 200 52 11 <.1 .02 8 275

25 38 4.7 2.4 .76 138 6.9 1.5 <.1 <.01 12 134

26 49 4.7 6.9 .87 108 55 4.3 <.1 .01 5.9 198

27 45 5.6 3.6 .83 159 5.3 3.8 <.1 <.01 12 159

28 40 5.6 3.6 .90 157 3.8 2.3 <.1 <.01 12 147

29 44 6.4 3.2 1.0 177 ———— 14 —

30 44 6.1 4.7 .75 155 7.6 5.1 <.1 <.01 11 152

Public-supply survey

31 56 5.7 7.7 0.89 122 62 6.5 <.1 .01 6.3 213

32 30 7.7 3.8 1.0 126 11 .6 <.1 .01 12 127

33 25 7.3 3.2 .90 110 7.1 2.0 <.1 .02 13 119

34 — — —— 94 ————— —

35 6.3 4.1 34 4.2 122 .3 9.3 .25 <.01 46 167

National median concentration for drinking-water aquifers

— — — — — — ————— 298
APPENDIXES 41

1Estimated values.

Appendix 3. Concentrations of nutrients and dissolved organic carbon in water sampled from wells

in Cook Inlet Basin, 1999

[Well number: See table 1 and fig. 2. Number in parentheses above property or constituent is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in computerized data bases. National median concentrations for major 

aquifers are from Nolan and Stoner (2000). <, less than; —, not applicable]

Well

number 

Concentrations

(milligrams per liter)

(00608)

Ammonia,

as N

(00623)

Ammonia +

organic nitrogen,

as N

(00631)

Nitrite +

nitrate,

as N

(00613)

Nitrite,

as N

(00666)

Phosphorus,

as P

(00671)

Orthophosphate,

as P

(00681)

Dissolved

organic

carbon

Subunit survey

1 <0.02 <.1 0.12 <.01 0.057 0.055 0.8

2 .1 .14 <.05 <.01 .218 .211 .8

3 .82 .82 <.05 <.01 .115 .125 1.2

4 <.02 <.1 .07 <.01 .016 .017 1.1

5 <.02 1

.1 <.05 <.01 <.004 <.01 1.2

6 .19 .25 <.05 <.01 .117 .103 1.7

7 <.02 .11 1.9 <.01 <.004 <.01 .5

8 <.02 1

.1 .48 <.01 <.004 <.01 .8

9 .8 .73 <.05 <.01 .384 .429 1.7

10 <.02 <.1 .21 <.01 .020 .015 .6

11 <.02 <.1 <.05 <.01 .037 .032 .8

12 .12 .13 <.05 <.01 .077 .062 .8

13 .03 <.1 <.05 <.01 .031 .021 1.1

14 <.02 <.1 .12 <.01 .004 <.01 2.1

15 <.02 <.1 <.05 <.01 <.004 <.01 .7

16 .11 .17 <.05 <.01 .100 .087 .8

18 .35 .36 <.05 .01 <.004 .014 1.4

19 <.02 <.1 .81 <.01 <.004 <.01 1.0

20 <.02 <.1 .44 <.01 <.004 <.01 .9

21 <.02 <.1 .56 <.01 <.004 <.01 .3

22 <.02 .1 3.5 <.01 <.004 <.01 .6

23 <.02 1

.1 4.8 <.01 .011 .012 1.0

24 <.02 1.1 1.8 <.01 <.006 .012 .6

25 <.02 <.1 .37 <.01 .026 .018 .8

26 <.02 <.1 .50 <.01 <.004 <.01 .9

27 <.02 <.1 .91 <.01 .006 <.01 .9

28 <.02 <.1 .15 .01 .009 <.01 .8

29 .05 .12 .17 <.01 .012 <.01 .9

30 .03 .14 <.05 <.01 .011 .01 1.0

Public-supply survey

31 <0.02 <0.1 0.58 <0.01 <0.004 <0.01 0.4

32 <.02 <.1 .19 <.01 .014 <.01 .3

33 <.02 1

.1 .25 <.01 .014 .019 .3

34 <.02 1

.1 2.5 <.01 <.004 <.01 .6

35 .31 .31 <.05 <.01 .370 .446 1.9

National median concentration for major aquifers

— 0.02 <0.2 0.48 <0.01 — 0.01 —
42 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

1Estimated values.2Concentrations of manganese were determined by using two methods.

Appendix 4. Concentrations of trace elements in water sampled from wells in Cook Inlet Basin, 1999[Well number: See table 1 and fig. 2. Number in parentheses above constituent is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in computerized data bases. Highlighted values exceed a drinking-water-quality standard or a proposed standard. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(01106)

Aluminum

(01095)

Antimony

(01000)

Arsenic

(01005)

Barium

(01010)

Beryllium

(01025)

Cadmium

(01030)

Chromium

(01035)

Cobalt

(01040)

Copper

(01046)

Iron

(01049)

Lead

(01056)

Manganese2 (01060)

Molybdenum

(01065)

Nickel

(01145)

Selenium

(01075)

Silver

(22703)

Uranium

(01090)

Zinc First

method

Second

method

Subunit survey

1 <1 <1 6 1.8 <1 <1 <1 <1 <1 390 <1 28 30 <1 1.2 <1 <1 <1 1.8

2 <1 <1 19 8.7 <1 <1 <1 <1 <1 1,100 <1 590 541 <1 <1 <1 <1 <1 56

3 1.4 <1 2 133 <1 <1 <1 <1 <1 160 <1 28 29 <1 <1 <1 <1 <1 214 1.4 <1 <1 3.9 <1 <1 <1 <1 1 17 <1 68 65 <1 <1 <1 <1 <1 12

5 <1 <1 3 65 <1 <1 <1 <1 <1 7,300 <1 290 295 <1 <1 <1 <1 <1 1.0

6 2.5 <1 15 23 <1 <1 <1 <1 <1 15 <1 120 108 2.4 <1 <1 <1 <1 39

7 <1 <1 1 6.8 <1 <1 <1 <1 15 <10 <1 <3 <1 <1 1.1 <1 <1 <1 4.88 <1 <1 1 9.4 <1 <1 <1 <1 1.3 <10 <1 <3 <1 <1 1.4 <1 <1 <1 169 <1 <1 22 106 <1 <1 <1 <1 <1 180 <1 280 288 <1 <1 <1 <1 <1 9.9

10 <1 <1 3 1.3 <1 <1 <1 <1 10 19 <1 <3 <1 <1 <1 <1 <1 <1 1.6

11 <1 <1 6 26 <1 <1 <1 <1 <1 1,100 <1 67 63 <1 <1 <1 <1 <1 4.4

12 <1 <1 1 7.9 <1 <1 <1 <1 <1 110 <1 580 591 <1 <1 <1 <1 <1 76

13 <1 <1 10 43 <1 <1 <1 <1 <1 330 <1 180 170 1.5 <1 <1 <1 <1 1.5

14 <1 <1 3 21 <1 <1 — <1 <1 19 <1 170 157 <1 1.9 <1 <1 <1 5.8

15 <1 <1 <1 2.7 <1 <1 — <1 8.3 48 <1 12 3 <1 <1 <1 <1 <1 25

16 <1 <1 2 5.7 <1 <1 <1 <1 1.8 17 5 100 102 1.8 <1 <1 <1 <1 18

18 <1 <1 29 18 <1 <1 — 1.8 <1 18,000 <1 1,500 1,460 <1 1.1 <1 <1 <1 9.3

19 <1 <1 <1 9.0 <1 <1 — <1 4.1 <10 <1 <3 <1 <1 1.1 <1 <1 <1 2020 <1 <1 <1 7.6 <1 <1 1.1 <1 1.3 <10 <1 <3 <1 <1 1.5 <1 <1 <1 2321 <1 <1 <1 3.3 <1 <1 <1 <1 <1 <10 <1 <3 <1 <1 <1 <1 <1 <1 3.822 4.9 <1 <1 7.9 <1 <1 2.1 <1 3.1 <10 <1 <3 <1 <1 <1 <1 <1 <1 5623 <1 <1 1 9.6 <1 <1 3 <1 8.8 <10 <1 <3 <1 <1 <1 <1 <1 <1 2024 <1 <1 <2 34 <1 <1 <.8 <1 1.2 <10 <1 <2 <1 <1 1.1 <2 <1 <1 1.125 1.7 <1 2 3.5 <1 <1 <1 <1 12 <10 <1 <2 <1 <1 1 <1 <1 <1 4826 1.4 <1 <1 13 <1 <1 <1 <1 3.6 15 <1 <3 <1 1.5 1.3 <1 <1 <1 <1

27 <1 <1 2 9.1 <1 <1 <1 <1 14 <10 <1 <3 <1 <1 1.2 <1 <1 <1 8.128 1.4 <1 1 8.1 <1 <1 — <1 3 <10 <1 58 55 <1 <1 1 <1 <1 16

29 <1 <1 <1 30 <1 <1 <1 <1 <1 63 <1 79 76 <1 1.3 <1 <1 <1 2230 1.4 <1 7 16 <1 <1 <.8 <1 <1 85 <1 52 48 <1 <1 <2 <1 <1 10

Public-supply survey

31 1.2 <1 <1 19 <1 <1 <1 <1 <1 <10 <1 <3 <1 1.4 1.8 <1 <1 <1 1.332 <1 <1 <1 3.8 <1 <1 <1 <1 <1 <10 <1 <3 <1 <1 <1 <1 <1 <1 2.133 <1 <1 1 2.8 <1 <1 1 <1 <1 <10 <1 <3 <1 1.6 <1 1 <1 <1 1.034 1.2 <1 <1 5.8 <1 <1 <1 <1 1.6 — <1 — <1 <1 <1 <1 <1 <1 1.335 1.1 <1 24 52 <1 <1 <1 <1 <1 87 <1 38 38 2.1 <1 <1 <1 <1 <1
APPENDIXES 43

Appendix 5. Concentrations of pesticides in water sampled from wells in Cook Inlet Basin, 1999

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(82660)2,6-Diethylaniline(49260)Acetochlor(46342)Alachlor(39632)Atrazine(04040)Deethylatrazine(82686)Methyl azinphos(82673)Benfluralin(04028)Butylate(82680)Carbaryl(82674)Carbofuran(38933)Chlorpyrifos(04041)Cyanazine(82682)Dacthal (DCPA)(34653)p,p’-DDE(39572)Diazinon

Subunit survey

1 <0.003 <0.002 <0.002 <0.001 <0.002 <0.001 <0.002 <0.002 <0.003 <0.003 <0.004 <0.004 <0.002 <0.006 <0.002

2 <.003 <.002 <.002 <.001 <.002 <.02 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

3 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

4 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 1

.002 <.002

5 <.003 <.002 <.002 <.001 <.002 1.007 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

6 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

7 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

8 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

9 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

10 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

11 <.003 <.002 <.002 <.001 1

.0015 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

12 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

13 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

14 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

15 <.003 <.002 <.002 <.074 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

16 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

18 <.003 <.002 <.002 <.001 <.002 <.02 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

19 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

20 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

21 — — — — — — — — — — — — — — —

22 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

23 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

24 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 1

.002 <.002

25 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

26 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

27 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

28 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

29 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

30 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

Public-supply survey

31 <0.003 <0.002 <0.002 <0.001 <0.002 <0.001 <0.002 <0.002 <0.003 <0.003 <0.004 <0.004 <0.002 10.002 <0.002

32 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

32 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

34 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002

35 <.003 <.002 <.002 <.001 <.002 <.001 <.002 <.002 <.003 <.003 <.004 <.004 <.002 <.006 <.002
44 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Appendix 5. Concentrations of pesticides in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(39381)Dieldrin(82677)Disulfoton(82668)EPTC(82663)Ethalfluralin(82672)Ethoprophos(04095)Fonofos(34253)alpha-HCH(39341)Lindane(82666)Linuron(39532)Malathion(82667)Methyl parathion(39415)Metolachlor(82630)Metribuzin(82671)Molinate(82684)Naprop amide

Subunit survey

1 <0.001 <0.017 <0.002 <0.004 <0.003 <0.003 <0.002 <0.004 <0.002 <0.005 <0.006 <0.002 <0.004 <0.004 <0.003

2 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

3 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

4 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

5 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

6 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

7 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

8 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

9 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

10 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

11 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

12 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

13 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

14 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

15 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

16 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

18 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

19 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

20 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

21 — — — — — — — — — — — — — — —

22 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

23 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

24 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

25 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

26 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

27 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

28 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

29 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

30 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

Public-supply survey

31 <0.001 <0.017 <0.002 <0.004 <0.003 <0.003 <0.002 <0.004 <0.002 <0.005 <0.006 <0.002 <0.004 <0.004 <0.003

32 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

32 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

34 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003

35 <.001 <.017 <.002 <.004 <.003 <.003 <.002 <.004 <.002 <.005 <.006 <.002 <.004 <.004 <.003
APPENDIXES 45

Appendix 5. Concentrations of pesticides in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(39542)Parathion(82669)Pebulate(82683)Pendimethalin(82687)cis-Permethrin(82664)Phorate(04037)Prometon(82676)Pronamide(04024)Propachlor(82679)Propanil(82685)Propargite(04035)Simazine(82670)Tebuthiuron(82665)Terbacil(82675)Terbufos(82681)Thiobencarb

Subunit survey

1 <0.004 <0.004 <0.004 <0.005 <0.002 <0.018 <0.003 <0.007 <0.004 <0.013 <0.005 <0.01 <0.007 <0.013 <0.002

2 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

3 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

4 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

5 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

6 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

7 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

8 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

9 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

10 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

11 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 1

.002 <.013 <.005 1.004 <.007 <.013 <.002

12 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

13 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

14 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

15 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

16 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

18 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

19 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

20 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

21 — — — — — — — — — — — — — — —

22 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

23 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

24 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 -- <.005 <.01 <.007 <.013 <.002

25 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

26 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

27 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

28 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

29 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

30 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.080 <.005 <.01 <.007 <.013 <.002

Public-supply survey

31 <0.004 <0.004 <0.004 <0.005 <0.002 <0.018 <0.003 <0.007 <0.004 <0.013 <0.005 <0.077 <0.007 <0.013 <0.002

32 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

32 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.077 <.007 <.013 <.002

34 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002

35 <.004 <.004 <.004 <.005 <.002 <.018 <.003 <.007 <.004 <.013 <.005 <.01 <.007 <.013 <.002
46 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Appendix 5. Concentrations of pesticides in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(82678)Triallate(82661)Trifluralin(39732)2,4-D(38746)2,4-DB(49310)Carbaryl(49309)Carbofuran(49308)3-Hydroxycarbofuran(49315)Acifluorfen(49312)Aldicarb(49313)Aldicarb sulfone(49314)Aldicarb sulfoxide(38711)Bentazon(61693)Methyl bensul furon(04029)Bromacil(49311)Bromoxynil

Subunit survey

1 <0.001 <0.002 <0.077 <0.054 <0.063 <0.057 <0.062 <0.062 <0.082 <0.16 <0.027 <0.019 <0.048 <0.081 <0.057

2 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

3 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

4 <.001 <.002 <.077 <.054 <.063 <.057 <.062 — <.082 <.16 <.027 <.019 <.048 <.081 <.057

5 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

6 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

7 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

8 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

9 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

10 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

11 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

12 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

13 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

14 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

15 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

16 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

18 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

19 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

20 <.001 <.002 —————————————

21 — — <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

22 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

23 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

24 <.001 <.002 <.077 <.054 <.063 1

.0008 1.0013 — <.082 <.16 <.027 <.019 <.048 <.081 <.057

25 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

26 <.001 <.002 <.077 <.054 <.063 <.057 <.062 — <.082 <.16 <.027 <.019 <.048 <.081 <.057

27 <.001 <.002 <.077 <.054 <.063 <.057 <.062 — <.082 <.16 <.027 <.019 <.048 <.081 <.057

28 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

29 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

30 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

Public-supply survey

31 <0.001 <0.002 <0.077 <0.054 <0.063 <0.057 <0.062 <0.062 <0.082 <0.16 <0.027 <0.019 <0.048 <0.081 <0.057

32 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

32 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

34 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057

35 <.001 <.002 <.077 <.054 <.063 <.057 <.062 <.062 <.082 <.16 <.027 <.019 <.048 <.081 <.057
APPENDIXES 47

Appendix 5. Concentrations of pesticides in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(49306)Chlorothalonil(49305)Clopyralid(49304)Dacthal monoacid(38442)Dicamba(49302)Dichlorprop(49301)Dinoseb(49300)Diuron(49297)Fenuron(38811)Fluometuron(61694)Flumetsulam(61695)Imidacloprid(38482)MCPA(38487)MCPB(38501)Methiocarb(61696)Methomyloxime

Subunit survey

1 <0.049 <0.041 <0.072 <0.096 <0.05 <0.043 <0.079 <0.074 <0.062 <0.087 <0.106 <0.059 <0.063 <0.08 <0.01

2 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

3 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

4 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

5 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

6 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

7 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

8 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

9 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

10 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

11 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

12 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

13 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

14 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 1.007 <.087 <.106 <.059 <.063 <.08 <.01

15 <.049 <.041 <.072 <.096 <.05 <.043 1.002 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

16 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

18 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

19 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

20 — — — — — — — — — — — — — — —

21 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

22 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

23 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

24 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

25 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

26 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

27 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

28 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

29 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

30 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

Public-supply survey

31 <0.049 <0.041 <0.072 <0.096 <0.05 <0.043 1

0.002 <0.074 <0.062 <0.087 <0.106 <0.059 <0.063 <0.08 <0.01

32 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

32 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

34 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01

35 <.049 <.041 <.072 <.096 <.05 <.043 <.079 <.074 <.062 <.087 <.106 <.059 <.063 <.08 <.01
48 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

1Detected in sample; estimated value.

Appendix 5. Concentrations of pesticides in water sampled from wells in Cook Inlet Basin, 

1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. 

Geological Survey to identify parameter in computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(49296)Methomyl(61697)Metsulfuron methyl(49294)Neburon(49293)Norflur azon(49292)Oryzalin(38866)Oxamyl(49291)Picloram(49236)Propham(38538)Propoxur(49235)Triclopyr(61692)3(4-Chlorophenyl)methyl urea

Subunit survey

1 <0.077 <0.114 <0.075 <0.077 <0.071 <0.016 <0.071 <0.072 <0.059 <0.101 <0.092

2 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

3 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

4 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

5 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

6 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

7 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

8 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

9 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

10 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

11 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

12 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

13 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

14 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

15 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

16 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

18 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

19 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

20 — — — — — — — — — — —

21 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

22 <.077 <.114 1

.0008 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

23 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

24 <.077 1

.002 1.0011 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

25 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

26 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

27 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

28 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

29 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

30 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

Public-supply survey

31 <0.077 <0.114 <0.075 <0.077 <0.071 <0.016 <0.071 <0.072 <0.059 <0.101 <0.092

32 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

32 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

34 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092

35 <.077 <.114 <.075 <.077 <.071 <.016 <.071 <.072 <.059 <.101 <.092
APPENDIXES 49

Appendix 6. Concentrations of volatile organic compounds in water sampled from wells in Cook Inlet Basin, 1999

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(34506)1,1,1-Trichloroethane(34511)1,1,2-Trichloroethane(34496)1,1-Dichloroethane(34501)1,1-Dichloroethylene(77168)1,1-Dichloropropene(77443)1,2,3-Trichloropropane(77651)1,2-Dibromoethane(32103)1,2-Dichloroethane(34541)1,2-Dichloropropane(34546)trans-1,2-Dichloroethylene(77170)2,2-Dichloropropane(73547)trans-1,4-Dichloro-2-butene(77103)2-Hexanone(81552)Acetone(34215)Acrylo nitrile

Subunit survey

1 <0.032 <0.064 <0.066 <0.044 <0.026 <0.16 <0.036 <0.13 <0.068 <0.032 <0.078 <0.7 <0.7 <5 <1.2

2 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

3— — — — — — — — — — — — — — —

4 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

5 <.032 <.06 <.066 <.04 <.026 <.16 <.036 <.13 <.068 <.032 <.05 <.7 <.7 <7 <1.2

6 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

7 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

8 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

9 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

10 1

.031 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

11 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

12 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

13 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

14 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

15 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

16 <.032 <.06 <.066 <.04 <.026 <.16 <.036 <.13 <.068 <.032 <.05 <.7 <.7 <7 <1.2

18 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

19 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

20 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

21 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

22 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

23 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

24 1.025 <.06 <.066 <.04 <.026 <.16 <.036 <.13 <.068 <.032 <.05 <.7 <.7 <7 <1.2

25 <.032 <.06 <.066 <.04 <.026 <.16 <.036 <.13 <.068 <.032 <.05 <.7 <.7 <7 <1.2

26 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

27 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

28 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

29 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

30 <.032 <.06 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.05 <.7 <.7 <7 <1.2

Public-supply survey

31 <0.032 <0.064 <0.066 <0.044 <0.026 <0.16 <0.036 <0.13 <0.068 <0.032 <0.078 <0.7 <0.7 <5 <1.2

32 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

32 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

34 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2

35 <.032 <.064 <.066 <.044 <.026 <.16 <.036 <.13 <.068 <.032 <.078 <.7 <.7 <5 <1.2
50 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Appendix 6. Concentrations of volatile organic compounds in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(77613)1,2,3-Trichlorobenzene(77221)1,2,3-Trimethylbenzene(34551)1,2,4-Trichlorobenzene(77222)1,2,4-Trimethylbenzene(77226)1,3,5-Trimethylbenzene(34566)1,3-Dichlorobenzene(34571)1,4-Dichlorobenzene(77223)Isopropylbenzene(77342)Butylbenzene(77224)n-Propylbenzene(34536)1,2-Dichlorobenzene(77350)sec-Butylbenzene(77353)tert-Butylbenzene(34030)Benzene(81555)Bromobenzene

Subunit survey

1 <0.27 <0.12 <0.19 1.038 <0.044 <0.054 <0.05 <0.032 <0.19 <0.042 <0.048 <0.048 <0.1 <0.1 <0.036

2 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

3— — — — — — — — — — — — — — —

4 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

5 <.27 <.12 <.19 .17 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.032 <.06 <.035 <.036

6 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

7 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

8 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

9 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

10 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

11 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

12 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

13 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

14 <.27 <.12 <.19 1

.014 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

15 <.27 <.12 <.19 1.019 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

16 <.27 <.12 <.19 .16 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.032 <.06 <.035 <.036

18 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

19 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

20 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

21 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

22 <.27 <.12 <.19 1.093 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

23 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

24 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.032 <.06 <.035 <.036

25 <.27 <.12 <.19 .16 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.032 <.06 <.035 <.036

26 <.27 <.12 <.19 1.092 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

27 <.27 <.12 <.19 1.055 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

28 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

29 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

30 <.27 <.12 <.19 1

.035 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.032 <.06 <.035 <.036

Public-supply survey

31 <0.27 <0.12 <0.19 <0.056 <0.044 <0.054 <0.05 <0.032 <0.19 <0.042 <0.048 <0.048 <0.1 <0.1 <0.036

32 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

32 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

34 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036

35 <.27 <.12 <.19 <.056 <.044 <.054 <.05 <.032 <.19 <.042 <.048 <.048 <.1 <.1 <.036
APPENDIXES 51

Appendix 6. Concentrations of volatile organic compounds in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(50002)Bromoethene(32104)Bromoform(77041)Carbon disulfide(32102)Tetrachloromethane(carbon tetrachloride)(34301)Chlorobenzene(32105)Dibromochloromethane(34311)Chloroethane(32106)Chloroform(77093)cis-1,2-Dichloroethylene(34704)cis-1,3-Dichloropropene(82625)1,2-Dibromo-3-chloropropane(30217)Dibromomethane(32101)Bromodichloromethane(34668)Dichlorodifluoromethane(CFC-12)(81577)Di-isopropylether

Subunit survey

1 <0.1 <0.1 <0.37 <0.088 <0.028 <0.18 <0.12 <0.052 <0.038 <0.09 <0.21 <0.05 <0.048 <0.14 <0.1

2 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.1

3— — — — — — — — — — — — — — —

4 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.1

5 <.1 <.06 <.07 <.06 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.27 <.1

6 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.1

7 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.1

8 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

9 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

10 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.1

11 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

12 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

13 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

14 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

15 <.1 <.1 <.37 <.088 <.028 <.18 <.12 1.011 <.038 <.09 <.21 <.05 <.048 <.14 <.098

16 <.1 <.06 <.07 <.06 1

.007 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.27 <.098

18 <.1 <.1 1.05 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

19 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

20 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

21 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

22 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

23 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

24 <.1 <.06 <.07 <.06 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.27 <.1

25 <.1 <.06 <.07 <.06 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.27 <.1

26 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

27 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

28 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

29 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

30 <.1 <.06 <.07 <.06 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.27 <.1

Public-supply survey

31 <0.1 <0.1 <0.37 <0.088 <0.028 <0.18 <0.12 <0.052 <0.038 <0.09 <0.21 <0.05 <0.048 <0.14 <0.098

32 <.1 <.1 <.37 <.088 <.028 <.18 <.12 1.023 <.038 <.09 <.21 <.05 <.048 <.14 <.098

32 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

34 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098

35 <.1 <.1 <.37 <.088 <.028 <.18 <.12 <.052 <.038 <.09 <.21 <.05 <.048 <.14 <.098
52 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Appendix 6. Concentrations of volatile organic compounds in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(77562)1,1,1,2-Tetrachloroethane(34516)1,1,2,2-Tetrachloroethane(34396)Hexachloroethane(81576)Diethyl ether(50004)Ethyl tert-butyl ether(50005)tert-Pentyl methyl ether(34371)Ethylbenzene(77652)1,1,2-Trichlorotrifluoroethane(CFC-113)(81607)Tetrahydrofuran(39702)Hexachlorobutadiene(50000)1,2,3,5-Tetramethylbenzene(isodurene)(73570)Ethyl methacrylate(81597)Methyl methacrylate(81593)Methyl acrylonitrile(77297)Bromochloromethane

Subunit survey

1 <0.044 <0.13 <0.36 <0.17 <0.054 <0.11 <0.03 <0.032 <9 <0.14 <0.2 <0.28 <0.35 <0.57 <0.044

2 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

3— — — — — — — — — — — — — — —

4 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

5 <.03 <.09 <.19 <.17 <.054 <.11 <.03 <.06 <2.2 <.14 <.2 <.18 <.35 <.6 <.044

6 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

7 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

8 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

9 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

10 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

11 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

12 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

13 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

14 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

15 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

16 <.03 <.09 <.19 <.17 <.054 <.11 <.03 <.06 <2.2 <.14 <.2 <.18 <.35 <.6 <.044

18 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

19 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

20 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

21 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

22 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

23 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

24 <.03 <.09 <.19 <.17 <.054 <.11 <.03 <.06 <2.2 <.14 <.2 <.18 <.35 <.6 <.044

25 <.03 <.09 <.19 <.17 <.054 <.11 <.03 <.06 <2.2 <.14 <.2 <.18 <.35 <.6 <.044

26 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

27 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

28 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

29 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

30 <.03 <.09 <.19 <.17 <.054 <.11 <.03 <.06 <2.2 <.14 <.2 <.18 <.35 <.6 <.044

Public-supply survey

31 <0.044 <0.13 <0.36 <0.17 <0.054 <0.11 <0.03 <0.032 <9 <0.14 <0.2 <0.28 <0.35 <0.57 <0.044

32 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

32 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

34 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.14 <.2 <.28 <.35 <.57 <.044

35 <.044 <.13 <.36 <.17 <.054 <.11 <.03 <.032 <9 <.1 <.2 <.28 <.35 <.57 <.044
APPENDIXES 53

Appendix 6. Concentrations of volatile organic compounds in water sampled from wells in Cook Inlet Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in 

computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(49991)Methyl acrylate(77424)Methyl iodide(78032)Methyl tert-butylether (MTBE)(34413)Bromomethane(methyl bromide)(34418)Chloromethane2(methyl chloride)(34423)Dichloromethane(methylene chloride)(81595)2-Butanone (methylethyl ketone)(78133)4-Methyl-2-pentanone(85795)meta and para Xylene(34696)Naphthalene(77275)2-Chlorotoluene(77135)o-Xylene(77356)4-Isopropyl-1-methylbenzene(49999)1,2,3,4-Tetramethylbenzene (prehnitene)

Subunit survey

1 <1.4 <0.21 <0.17 <0.15 <0.25 <0.38 <1.6 <0.37 <0.06 <0.25 <0.042 <0.06 <0.11 <0.23

2 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

3—— — — — — —————— — —

4 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

5 <1.4 <.12 <.17 <.26 <.5 <.38 <1.6 <.37 1.041 <.25 <.042 <.038 <.07 <.23

6 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

7 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

8 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

9 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

10 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

11 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

12 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

13 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

14 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

15 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

16 <1.4 <.12 <.17 <.26 <.5 <.38 <1.6 <.37 <.06 <.25 <.042 <.038 <.07 <.23

18 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

19 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

20 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

21 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

22 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

23 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

24 <1.4 <.12 <.17 <.26 <.5 <.38 <1.6 <.37 <.06 <.25 <.042 <.038 <.07 <.23

25 <1.4 <.12 <.17 <.26 <.5 <.38 <1.6 <.37 <.06 <.25 <.042 <.038 <.07 <.23

26 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

27 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

28 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

29 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

30 <1.4 <.12 <.17 <.26 <.5 <.38 <1.6 <.37 1.031 <.25 <.042 <.038 <.07 <.23

Public-supply survey

31 <1.4 <0.21 <0.17 <0.15 <0.25 <0.38 <1.6 <0.37 <0.06 <0.25 <0.042 <0.06 <0.11 <0.23

32 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

32 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

34 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23

35 <1.4 <.21 <.17 <.15 <.25 <.38 <1.6 <.37 <.06 <.25 <.042 <.06 <.11 <.23
54 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

1

Estimated value.

2

Also detected in field blank.

3

Also detected in field and equipment blanks.

Appendix 6. Concentrations of volatile organic compounds in water sampled from wells in Cook Inlet 

Basin, 1999—Continued

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in computerized data bases. <, less than; —, not analyzed]

Well

number

Concentration

(micrograms per liter)

(77173)1,3-Dichloropropane(78109)3-Chloropropene(77128)Styrene(34475)Tetrachloroethylene(77220)o-Ethyltoluene(77277)4-Chlorotoluene(34010)Toluene3(34699)Trans-1,3-Dichloropropene(39180)Trichloroethylene(34488)Trichlorofluoromethane(CFC-11)(39175)Vinylchloride

Subunit survey

1 <0.12 <0.2 <0.042 <0.1 <0.1 <0.056 10.07 <0.13 <0.038 10.06 <0.11

2 <.12 <.2 <.042 <.1 <.1 <.056 1.01 <.13 <.038 <.09 <.11

3——————— — — — —

4 <.12 <.2 <.042 <.1 <.1 <.056 1.03 <.13 <.038 <.09 <.11

5 <.12 <.2 <.042 <.1 <.06 <.06 .77 <.09 <.038 .27 <.11

6 <.12 <.2 <.042 <.1 <.1 <.056 1.03 <.13 <.038 <.09 <.11

7 <.12 <.2 <.042 <.1 <.1 <.056 .18 <.13 <.038 1

.04 <.11

8 <.12 <.2 <.042 <.1 <.1 <.056 1.06 <.13 <.038 <.09 <.11

9 <.12 <.2 <.042 <.1 <.1 <.056 1.03 <.13 <.038 <.09 <.11

10 <.12 <.2 <.042 <.1 <.1 <.056 1.05 <.13 <.038 <.09 <.11

11 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

12 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

13 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

14 <.12 <.2 <.042 1.05 <.1 <.056 .17 <.13 <.038 1.1 <.11

15 <.12 <.2 <.042 <.1 <.1 <.056 1.09 <.13 <.038 <.09 <.11

16 <.12 <.2 <.042 <.1 <.06 <.06 1.02 <.09 <.038 .84 <.11

18 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

19 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

20 <.12 <.2 <.042 <.1 <.1 <.056 .54 <.13 <.038 <.09 <.11

21 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

22 <.12 <.2 <.042 <.1 <.1 <.056 1.03 <.13 <.038 <.09 <.11

23 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

24 <.12 <.2 <.042 <.1 <.06 <.06 1.01 <.09 <.038 <.09 <.11

25 <.12 <.2 <.042 <.1 <.06 <.06 1.05 <.09 <.038 .70 <.11

26 <.12 <.2 <.042 <.1 <.1 <.056 1.08 <.13 <.038 .44 <.11

27 <.12 <.2 <.042 <.1 <.1 <.056 1.02 <.13 <.038 <.09 <.11

28 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 1

.03 <.11

29 <.12 <.2 <.042 <.1 <.1 <.056 1.02 <.13 <.038 <.09 <.11

30 <.12 <.2 <.042 <.1 <.06 <.06 .19 <.09 <.038 1

.03 <.11

Public-supply survey

31 <0.12 <0.2 <0.042 <0.1 <0.1 <0.056 <0.05 <0.13 <0.038 <0.09 <0.11

32 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

32 <.12 <.2 <.042 <.1 <.1 <.056 <.05 <.13 <.038 <.09 <.11

34 <.12 <.2 <.042 <.1 <.1 <.056 1.01 <.13 <.038 <.09 <.11

35 <.12 <.2 <.042 <.1 <.1 <.056 1.02 <.13 <.038 <.09 <.11
APPENDIXES 55

1

Gilliom and others (1998).

Appendix 7. Activities of isotopes in water sampled from wells in Cook Inlet Basin, 1999

[Well number: See table 1 and fig. 2. Number in parentheses is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in computerized data bases. Highlighted values exceed a proposed water-quality standard (maximum contaminant level) for radon (U.S. Environmental Protection Agency, 2000). <, less than; —, not analyzed or not applicable]

Well

number

Radioactivity

(picocuries per liter)

(04126)Alpha, as thorium-230, dissolved(75987)Alpha (2-sigma precision)(03515)Gross beta, as cesium-137, dissolved(75989)Gross beta (2-sigma precision)(82303)Radon-222(76002)Radon-222 (2-sigma precision)(50833)Radium-224(50834)Radium-224 (2-sigma precision)(09503)Radium-226(76001)Radium-226 (2-sigma precision)(81366)Radium-228(76000)Radium-228 (2-sigma precision)

Subunit survey

1 <3 2.6 <4 4.1 190 21 <1 0.20 <1 0.09 <1 0.28

2 <3 2.6 <4 4.1 140 18 <1 .02 <1 .04 <1 .32

3 <3 4.4 <4 9.2 390 25 <1 .10 <1 .03 <1 .22

4 <3 2.3 <4 4.2 290 20 <1 .15 <1 .06 — —

5 <3 2.6 6.5 4.3 260 21 <1 .10 <1 .08 <1 .34

6 <3 2.2 <4 4.3 170 18 <1 .11 <1 .03 <1 .32

7 <3 2.6 <4 4.2 200 19 <1 .90 <1 .16 <1 .33

8 <3 2.6 <4 4.2 260 21 <1 .19 <1 .04 <1 .31

9 <3 2.3 10 5.1 — — <1 .10 <1 .04 <1 .26

10 <3 2.4 <4 4.1 500 25 <1 .20 <1 .04 <1 .28

11 <3 2.5 <4 4.2 240 20 <1 .12 <1 .03 <1 .38

12 <3 2.7 <4 4.1 610 27 <1 .10 <1 .03 <1 .38

13 <3 2.5 4.9 4.3 150 18 <1 .11 <1 .04 <1 .40

14 <3 2.7 <4 4.4 250 29 <1 .16 <1 .04 <1 .36

15 <3 2.2 <4 3.9 440 30 <1 .20 <1 .13 <1 .37

16 <3 2.8 <4 4.2 290 21 <1 .15 <1 .04 <1 .33

18 5.4 3.4 5.4 4.4 320 24 <1 .13 <1 .04 <1 .29

19 <3 2.7 <4 4.2 310 31 <1 .10 <1 .02 <1 .33

20 4.1 3.5 <4 4.3 320 21 <1 .24 <1 .12 <1 .26

21 <3 2.8 <4 4.0 320 28 <1 .36 <1 .10 <1 .29

22 <3 3.4 <4 4.4 180 18 <1 .62 <1 .19 <1 .24

23 <3 2.5 5.7 4.2 440 24 <1 .16 <1 .03 <1 .25

24 <3 2.3 4.9 4.4 220 20 <1 .10 <1 .05 <1 .38

25 <3 3.1 <4 4.2 210 18 <1 .38 <1 .10 <1 .41

26 <3 2.8 <4 4.2 — — <1 .46 <1 .09 <1 .33

27 <3 2.6 <4 4.2 — — <1 .15 <1 .04 <1 .31

28 <3 2.5 <4 4.1 200 18 <1 .10 <1 .12 <1 .30

29 <3 2.8 <4 4.3 450 24 <1 .10 <1 .02 <1 .19

30 <3 2.8 <4 4.4 150 28 <1 .20 <1 .07 <1 .47

Public-supply survey

31 <3 3.0 <4 4.4 140 18 <1 0.10 <1 0.03 <1 0.19

32 <3 2.7 4.8 4.1 580 27 <1 .11 <1 .04 <1 .37

32 <3 2.8 <4 3.9 380 37 <1 .50 <1 .09 <1 .30

34 <3 2.1 <4 3.9 240 27 <1 .22 <1 .08 <1 .37

35 <3 2.5 <4 4.1 200 19 <1 .10 <1 .02 <1 .22

National median concentration for drinking-water aquifers1

— — — — — 450 ———————
56 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

Appendix 8. Environmental isotopes of hydrogen and oxygen

in water sampled from wells in Cook Inlet Basin, 1999

[Well number: See table 1 and fig. 2. See table 2 regarding analytical methods used. 

Number in parentheses above ratio is number used by both U.S. Environmental Protection Agency and U.S. Geological Survey to identify parameter in computerized

data bases. —, not determined]

Well

number

Isotopic ratios

(per mil relative to

Vienna Standard Mean Ocean Water)

(82082)

Hydrogen-2 / Hydrogen-1

(82085)

Oxygen-18 / Oxygen-16

Subunit survey

1 -121 -16.0

2 -89 -9.1

3— —

4 -122 -15.9

5 -118 -15.2

6 -133 -17.0

7 -132 -17.2

8 -135 -17.0

9— —

10 -126 -16.3

11 -123 -15.9

12 -133 -17.2

13 -134 -17.3

14 -130 -16.5

15 -115 -13.1

16 -133 -16.9

18 -124 -15.3

19 -130 -16.7

20 -130 -16.9

21 -137 -17.9

22 — —

23 -131 -16.6

24 -159 -20.6

25 -128 -16.1

26 -164 -21.3

27 -126 -16.1

28 -125 -15.5

29 -129 -16.5

30 — —

Public-supply survey

31 -162 -21.1

32 -138 -17.9

33 -135 -17.6

34 -136 -17.4

35 -126 -16.0
APPENDIXES 57

1Estimated by Peter Schlosser and others, Lamont–Doherty Earth Observatory, written commun., 2000).

Appendix 9. Tritium analyses of water sampled from wells in Cook Inlet Basin, 1999

[Well number: See table 1 and fig. 2. —, not determined]

Well 

number

Sample date Apparent age1

(years)

Probable date of recharge

based on tritium analyses

(range of years,

in decimal format) (mm/dd/yy 

format)

(decimal

format) Estimate Error

Subunit survey

1 08/27/99 1999.65 20.2 0.3 1979.2–1979.8

2 08/10/99 1999.61 25.6 .3 1973.7–1974.3

3 08/27/99 1999.65 — — —

4 09/01/99 1999.67 23.9 .4 1975.4–1976.2

5 09/21/99 1999.72 25.9 .5 1973.3–1974.3

6 07/28/99 1999.57 55.3 22.1 1922.2–1966.4

7 08/03/99 1999.59 17.0 .6 1982.0–1983.2

8 08/03/99 1999.59 7.3 .4 1991.9–1992.7

9 08/11/99 1999.61 — — —

10 08/09/99 1999.60 15.7 .6 1983.3–1984.5

11 08/10/99 1999.61 21.0 .3 1978.3–1978.9

12 07/27/99 1999.57 29.7 .5 1969.4–1970.4

13 07/26/99 1999.56 17.6 2.2 1979.8–1984.2

14 08/04/99 1999.59 25.8 .4 1973.4–1974.2

15 08/06/99 1999.59 1.8 .6 1997.2–1998.4

16 09/13/99 1999.70 58.0 29.3 1912.4–1971.0

18 08/06/99 1999.59 30.1 .4 1969.1–1969.9

19 08/04/99 1999.59 15.2 .3 1984.1–1984.7

20 08/02/99 1999.58 32.0 1.4 1966.2–1969.0

21 07/30/99 1999.58 6.3 .6 1992.7–1993.9

22 08/25/99 1999.65 — — —

23 07/27/99 1999.57 16.0 .4 1983.2–1984.0

24 09/29/99 1999.74 6.5 .4 1992.8–1993.6

25 09/15/99 1999.70 7.1 .2 1992.4–1992.8

26 08/31/99 1999.66 .8 .5 1998.4–1999.4

27 08/30/99 1999.66 13.4 .3 1986.0–1986.6

28 08/16/99 1999.62 26.9 .4 1972.3–1973.1

29 08/23/99 1999.64 19.1 .4 1980.1–1980.9

30 10/20/99 1999.80 23.4 .4 1976.0–1976.8

Public-supply survey

31 08/24/99 1999.64 0.3 0.5 1998.8–1999.8

32 07/26/99 1999.56 29.1 0.5 1970.0–1971.0

33 07/21/99 1999.55 31.2 0.5 1967.9–1968.9

34 07/23/99 1999.56 2.0 0.6 1997.0–1998.2

35 08/11/99 1999.61 — — —
58 Ground-Water Quality, Cook Inlet Basin, Alaska, 1999

1

Estimated by G.C. Casile (U.S. Geological Survey, written commun., 2000).

Appendix 10. Chlorofluorocarbon analyses of water sampled from wells in Cook Inlet Basin, 1999

[Well number: See table 1 and fig. 2. Number in parentheses above chlorofluorocarbon is number used by both U.S. Environmental Protection Agency and 

U.S. Geological Survey to identify parameter in computerized data bases. Highlighted values are concentrations greater than possible for equilibrium with 

modern air. —, no data]

Well

number

Sample

date

Chlorofluorocarbons

(picograms per kilogram) Probable date of recharge1

based on concentrations

of chlorofluorocarbons

Remarks

(50281)

CFC-11

(50282)

CFC-12

(50283)

CFC-113

Subunit survey

1 08/27/99 5 100 5 About 1970

2 08/10/99 — 5 — Late 1940s CFC-11 and CFC-113 not detected

3 08/27/99 — — — — Sample not analyzed for CFCs

4 09/01/99 500 300 50 Late 1970s to about 1980

5 09/21/99 10 100 4 About 1970

6 07/28/99 1 1 — Mid-1940s CFC-113 not detected

7 08/03/99 300 3,000 50 About 1970

8 08/03/99 400 400 70 Early to mid-1980s

9 08/11/99 — — — — Sample not analyzed for CFCs

10 08/09/99 100 300 10 Late 1970s

11 08/10/99 1 10 — Early 1950s CFC-113 not detected

12 07/27/99 3 1 — Late 1940s or earlier CFC-113 not detected

13 07/26/99 10 500 7 Mid-1960s(?)

14 08/04/99 9,000 30 3 Mid-1960s

15 08/06/99 900 300 60 About 1980

16 09/13/99 1 1 4 Early 1940s

18 08/06/99 1 20 6 Probably pre-1940

19 08/04/99 3 20 — Late 1950s CFC-113 not detected

20 08/02/99 400 2,000 70 Early 1980s

21 07/30/99 90 300 20 Late 1970s

22 08/25/99 — — — — Sample not analyzed for CFCs

23 07/27/99 4 50 — About 1960 CFC-113 not detected

24 09/29/99 20,000 3,000 80 Early to mid-1980s

25 09/15/99 20 70 8 Mid-1960s

26 08/31/99 800 500 90 Late 1980s to 1990

27 08/30/99 300 500 5 Late 1980s or older

28 08/16/99 — 6 1 About 1950

29 08/23/99 80 3,000 4 Early 1960s

30 10/20/99 — — — — Sample not analyzed for CFCs

Public-supply survey

31 08/24/99 2,000 500 100 Early 1990s to present

32 07/26/99 9 60 3 Early to mid-1960s

32 07/21/99 20 5 — Late 1940s CFC-113 not detected

34 07/23/99 300 300 60 About 1980

35 08/11/99 — — — Probably pre-1940 No CFCs detected