&ER&
United States
Environmental Protection
Agency
EPA's Report on the Environment
Highlights of
National Trends
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We are pleased to present EPA's 2008 Report on the Environment: Highlights of
National Trends (ROE Highlights), which provides an important resource for the
general public for better understanding trends in our nation's health and envi-
ronment. This document presents some of the key findings from the more
comprehensive technical report, EPA's 2008 Report on the Environment (ROE )
in an easy to understand format.
These reports are the culmination of an effort begun over five years ago to
establish a set of scientifically sound measures, or indicators, that help answer
questions of vital importance to EPA's mission. Using these indicators, the
reports present what we know—and don't know—about the condition of air,
water, land, human health, and ecological condition in the United States. The
reports show both positive and negative trends.
We have made numerous improvements to the indicators as well as to the
indicator selection and reporting process. This included the extraordinary step
of having the ROE Highlights reviewed in a public forum to determine if citi-
zens—in addition to scientists—found the proposed indicators useful. Through
this open and transparent process, we have also created opportunities to
establish and strengthen our partnerships among federal, state, and non-
governmental organizations for data sharing and data needs planning to sup-
port indicator development and improvement.
These documents are not report cards on EPA's programs, nor do they inter-
pret the data or draw conclusions about the information presented. Instead,
the reports present the best available, scientifically sound information on
national-level environmental and health trends that are of interest to EPA and
the public and that may help to inform EPA's strategic planning.
We invite you to visit www.epa.gov/roe. There you will find the underlying
data, metadata, references and peer review documentation for the ROE indi-
cators as well as the full versions of the two reports. This website will be
updated periodically so the information remains current and relevant.
We welcome and encourage your involvement in this ongoing effort. You can
provide feedback to us at www.epa.gov/roe.
V
MOLLY O'NEILL GEORGE M. GRAY, PH.D.
Assistant Administrator for Environmental Assistant Administrator for Research
Information and Chief Information Officer and Development
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EPA's 2008 REPORT ON THE ENVIRONMENT:
HIGHLIGHTS OF NATIONAL TRENDS
The U.S. Environmental Protection
Agency (EPA) developed EPA's
2008 Report on the Environment
to help answer questions that are
of critical importance to the
Agency's mission to protect human
health and the environment. The
Report on the Environment doc-
uments trends in the condition of
the nation's environment and
human health and identifies signif-
icant gaps in our knowledge. It is
not intended to be a report card
on EPA's programs and activities.
CONTENTS
About This Document
Air 4
Outdoor Air 5
Acid Rain and Regional Haze 6
Ozone Depletion 7
Greenhouse Gases 8
Indoor Air 9
Water 10
Fresh Surface Waters 11
Ground Water 12
Wetlands 13
Coastal Waters 14
Drinking Water 15
Recreational Waters 16
Consumable Fish and Shellfish 17
Land 18
Land Cover 19
Land Use 20
Wastes and the Environment 21
Chemicals Applied and Released
to Land 22
Contaminated Lands 23
Human Exposure and Health 24
Exposure to Environmental
Contaminants 25
Health Status 26
Diseases and Health Conditions 27
Ecological Condition 28
Patterns in Ecological Systems 29
Biological Diversity 30
Ecological Processes 31
Physical and Chemical Attributes
of Ecological Systems 32
Ecological Exposure to Contaminants 33
Looking Ahead 34
List of Indicators 35
Acknowledgements 37
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ABOUT THIS DOCUMENT
Written for a general audience, this document, EPA's 2008 Report on the
Environment: Highlights of National Trends, summarizes some important
findings from a more comprehensive companion report, EPA's 2008 Report
on the Environment. An electronic version of the report, available at
www.epa.gov/roe, facilitates navigation and searching across both
documents.
Highlights of National Trends is organized around five chapters. Three of the
chapters (Air, Water, and Land) focus on trends in these environmental
media. The other two chapters address trends in human health and ecolog-
ical condition more broadly.
The chapters are divided into 25 topic pages. Each page summarizes what
we know—and don't know—about conditions and trends for the topic.
The information on these topics comes from highly reliable indicators (see
box below) and is based on the most recent data available from a variety
of governmental and non-governmental organizations.
Highlights of National Trends features a subset of indicators from the more
comprehensive Report on the Environment. The indicators were selected for
inclusion based on their importance to the public and to scientists, as well as
their ability to answer a series of key questions about the environment. These
key questions and 85 associated indicators form the framework of the Report
on the Environment and are listed at the end of this document.
In addition, only a few of the most important data gaps and limitations
from the Report on the Environment are included in Highlights of National
Trends. Readers are encouraged to consult the more comprehensive report
for more information. You can also read about some actions that individu-
als can take to protect the environment and their own health in the elec-
tronic version of Highlights of National Trends at www.epa.gov/roe.
ENVIRONMENTAL INDICATORS
The indicators used in the Report on the Environment:
• Rely on actual measurements of environmental and human health
conditions over time.
• Meet a set of standards, which include quality, accuracy, relevance,
and comparability.
• Were reviewed by an independent scientific panel to ensure that they
meet these standards.
• Are national (or in some cases regional) in coverage. They do not
describe trends or conditions for a specific locale.
• Come from many governmental and non-governmental organizations,
which collect data at different time periods and for varying purposes.
• Can only partially answer the key questions.
About This Document
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ABOUT THE DATA IN
THE REPORT ON THE
ENVIRONMENT
The indicators in the Report on the Environment are based on actual measure-
ments of the environment over time and do not describe activities to protect
the environment.
The length of time and geographic area over which consistent data have been
gathered varies from one indicator to another. Some indicators cover many
years, while others address only one point in time (a baseline for measuring
trends in the future). Most indicators in this report present data at the national
level, but some regional indicators have been used to illustrate important sce-
narios and could be applied to the nation in the future.
All of the indicators were reviewed by an independent panel and meet strict
definitions and criteria, including scientific quality and national (or in some
cases regional) coverage. Other sources of information are not included in this
report because they do not meet one or more of the criteria. While no data
sources are cited in Highlights of National Trends, sources for all data are avail-
able in the larger Report on the Environment document.
Each topic page in Highlights of National Trends acknowledges some of the
most important limitations of the indicators presented, or where gaps exist.
Data limitations are noted to provide the reader with information about the
quality or extent of the data presented that may affect the way in which they
are used. Data gaps are noted to identify areas or aspects of the environment
in which little or no measurement has been conducted. This report does not
propose actions to reduce data limitations or fill gaps.
UPDATES TO THE
REPORT ON THE
ENVIRONMENT
EPA's 2008 Report on the Environment brings together the most consistent
and reliable information on national environmental conditions and trends
currently available under a single cover. It builds on EPA's Draft Report on the
Environment 2003, which was the Agency's first effort to assemble scientifi-
cally sound indicators on the status and trends of the nation's environment.
Since the release of the 2003 report, EPA has revised, updated, and refined
the information in the Report on the Environment in response to scientific
developments as well as stakeholder feedback. EPA will publish periodic
updates of the Report on the Environment and use it to inform the Agency's
strategic planning process.
EPA's 2008 REPORT ON THE ENVIRONMENT
Highlights of National Trends is one of three products that collectively make up
EPA's 2008 Report on the Environment. The other two products are:
• EPA's 2008 Report on the Environment, the source of the information present-
ed in this document. The Report on the Environment is organized around key
questions about the environment and presents 85 indicators to help answer
those questions.
• A Web-based tool for navigating and searching EPA's 2008 Report on the
Environment and EPA's 2008 Report on the Environment: Highlights of National
Trends, available atwww.epa.gov/roe.
About This Document
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Outdoor Air
Acid Rain and Regional Haze
Ozone Depletion
Greenhouse Gases
Indoor Air
<"*lose to the Earth's surface, air provides the
oxygen and carbon dioxide needed to sus-
ta^tain human, animal, and plant life. Higher
up, a natural layer of ozone shields life on Earth
from the sun's harmful rays, and at all levels of the
atmosphere, naturally occurring greenhouse gases
help maintain a climate suitable for life. Indoors
and outdoors, from ground level to high above the
planet's surface, the condition of the air is critical to
human health and the environment.
Tracking the nation's air quality is challenging
because of the many sources, types, and effects of
air pollution. Most outdoor air pollutants can be
directly traced back to emissions sources that
release the pollutants into the air. However, some
air pollutants, such as ozone, are formed in the air
when an emission reacts with another airborne
substance.
Once airborne, pollutants can be transported
long distances by wind or transformed into other
compounds. They also can fall back to Earth, con-
taminating water and land. Both the amount of
pollutants emitted into the air and how these
pollutants move through the atmosphere deter-
mine air pollution levels, which are measured as
concentrations.
Many indicators are needed to characterize out-
door air quality separate from indoor air quality,
to characterize air quality trends at ground level
as well as higher in the atmosphere, and to char-
acterize both emissions and concentrations. Also,
air quality varies considerably with location and
time, which makes it challenging to obtain a
representative national picture.
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OUTDOOR AIR
Outdoor air pollutants come
from human activities such as
electricity production, industrial
processes, and transportation,
and from natural sources like wildfires and wind-blown
dust. Some of these pollutants can harm human health,
the environment, and other valued resources.
Beginning in the 1970s, EPA developed standards to pro-
tect human health and the environment from six com-
mon air pollutants that pose serious health and
environmental effects: carbon monoxide, lead, nitrogen
dioxide, ozone, airborne liquid and solid particles (known
KEY POINTS
as paniculate matter), and sulfur dioxide. These pollu-
tants are often referred to as criteria pollutants.
Subsequently, EPA identified an additional 188 pollutants
of concern, called air toxics, that are known or suspected
to cause cancer, other serious health problems, and
adverse environmental effects. Examples include ben-
zene, which is found in gasoline; metals such as mercury
and cadmium; dioxin; and asbestos.
There are several ways to measure outdoor air pollution
trends. Emissions can be measured or estimated at their
source, and concentrations of pollutants in the air can be
monitored at numerous outdoor locations around the
country.
Nationwide, emissions of criteria pollutants (or the
pollutants that form them) due to human activities
have decreased. Between 1990 and 2002, emissions of
carbon monoxide, volatile organic compounds (which
lead to the formation of ozone), particulate matter, sul-
fur dioxide, and nitrogen oxides (which lead to the for-
mation of ozone and particulate matter) decreased by
differing amounts, ranging from 17 to 44 percent. For
lead, emissions have decreased by 99 percent, but this
reduction is based on data that span a longer time
frame (19 70 to 2002).
Outdoor air concentrations of carbon monoxide,
lead, nitrogen dioxide, ozone, and particulate
matter have decreased over the decades during
which the current nationwide monitoring net-
work has operated. These reductions are consistent
with the observed decreases in emissions mentioned
above. In most or all of the United States, outdoor air
concentrations of carbon monoxide, lead, and nitro-
gen dioxide have decreased such that levels now
meet EPA's standards to protect human health and
the environment. Though outdoor air concentrations
of ozone (see graphic) and particulate matter have
decreased nationwide, concentrations still exceed
EPA's standards for either or both pollutants in
dozens of metropolitan areas.
.
spro-
\
For selected air toxics, emissions due to human
activities and outdoor air concentrations have
decreased. Nationwide, emissions summed across all
188 air toxics decreased between 1990 and 2002. This
includes a 52-percent reduction in mercury emissions.
Monitoring networks are extensive enough to deter-
mine corresponding national trends in outdoor air con-
centrations of benzene, which decreased 55 percent
between 1994 and 2006.
National indicators are not available for other
aspects of outdoor air quality. While indicators
vide insights on emissions and outdoor air concentra-
tion trends for many pollutants, monitoring networks
are not yet extensive enough to determine national
trends in concentrations for all pollutants, including
many air toxics. Further, the indicators are limited in
quantifying how exposures to single pollutants and
mixtures of air pollutants affect human health and the
environment. Although strong evidence links outdoor
air pollution to health effects at specific locations, few
long-term studies at a national scale have measured
the extent to which health effects are linked directly
to outdoor air quality.
Ozone Concentrations in Outdoor Air,
1978-2006
0.14
| 0.12
E 0.101
03
Q.
2 0.08
ro
~^ 0.06
o
I 0.04
d
<= 0.02
o
0.00
78
90% of sites have concentrations below this line
10% of sites have
concentrations
below this line
'EPA's air quality
standard
'90-'92 '94-'96 '98-'00 '02-'04
Concentrations were measured at 201 trend sites nationwide and are
expressed in terms of EPA's air quality standard.
The figure displays the 1997 National Ambient Air Quality Standard
(0.08 ppm). Future versions of the Report on the Environment m\\
compare ozone concentrations to the recently promulgated 2008
NAAQS (0.075 ppm) or to the NAAQS in effect at the time.
.Source: U.S. Environmental Protection Agency, 2007
Chapter 1 Air
Outdoor Air
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ACID RAIN AND REGIONAL HAZE
Each year in the United States,
millions of tons of sulfur dioxide
and nitrogen oxides are released
into the air from the burning of
fossil fuels. These pollutants react with other airborne
substances to form acidic compounds (sulfates and
nitrates). Acid deposition occurs when these compounds
fall to the Earth in one of two forms: wet (dissolved in
rain, snow, and fog) or dry (as gases or particles). Wet
deposition is more commonly referred to as acid rain.
Acid deposition is of concern because it can make soils,
lakes, and streams more acidic, which can harm fish,
amphibians, water birds, and other species in affected
areas. It can also damage trees, buildings, monuments,
KEY POINTS
painted surfaces, and other materials. Acid rain can be
tracked in several ways: by evaluating emissions of sulfur
dioxide and nitrogen oxides (the pollutants that form
sulfates and nitrates), by monitoring acid rain directly,
and by measuring the acidity of water bodies.
The pollutants that form acid rain also form airborne
particulate matter, which contributes to regional haze.
Regional haze, tracked by visibility measurements, is
caused when sunlight encounters tiny airborne particles
that limit the distance one can see. Regional haze also
degrades the color, clarity, and contrast of vistas, includ-
ing those found in many National Parks and Wilderness
Areas. Certain substances impair visibility more during
humid conditions.
Nationwide, emissions of the main pollutants that
form acid rain decreased between 1990 and 2002.
Emissions of sulfur dioxide due to human activities
decreased by 37 percent, and emissions of nitrogen
oxides due to human activities declined by 17 percent.
Acid rain, as measured by wet deposition of sul-
fates and nitrates, decreased across most of the
country from 1989 to 2006. Consistent with emis-
sions data, average regional decreases in wet deposi-
tion of sulfate during this time were 35 percent in the
Northeast, 33 percent in the Midwest, 28 percent in
the Mid-Atlantic, and 20 percent in the Southeast (see
graphic). Wet deposition of nitrate also decreased in
some parts of the country, but to a lesser extent than
wet deposition of sulfate.
\
Wet Sulfate Deposition, 1989-1991 Versus 2004-2006
Many surface waters in the Adirondack Mountains,
New England, and the northern Appalachian
regions became less acidic between the early 1990s
and 2005. This change corresponds to a decrease in
acid rain in these regions. While acidic surface waters
are still found in these areas, some surface waters are
showing signs of recovery. National indicators are not
available to track trends in other ways that acid rain has
harmed the environment or human health.
Regional haze in 38 National Parks and Wilderness
Areas improved between 1992 and 2004, with the
average annual visual range (or distance that one can
see) gradually increasing. On average, the West has
substantially better visibility than the East due to regional
differences in air pollution and the greater humidity in
the East. National indicators have not been developed to
track visibility in cities or other populated areas.
2004-2006
Source: National Atmospheric Deposition Program, 2007
Wet sulfate deposition (kilograms per hectare):
0 4 8 12 16 20 24 28 >32
Chapter 1 Air
Acid Rain and Regional Haze
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OZONE DEPLETION
Ozone is a gas present through-
out the Earth's atmosphere. Most
ozone is concentrated in a layer
in the stratosphere—a portion of
the atmosphere many miles above the planet's surface.
The ozone layer protects people, animals, plants, and other
living things by absorbing most of the sun's harmful ultra-
violet radiation, which can lead to more cases of certain
types of skin cancer and cataracts and can harm crops and
ecosystems. In contrast, ozone in the troposphere (the por-
tion of the atmosphere from ground level to the strato-
sphere) is a pollutant that poses a health risk.
Certain ozone-depleting substances, which are man-made
and emitted at ground level by sources worldwide, have
been damaging the ozone layer for many years. Once
these chemicals rise from the troposphere into the strato-
sphere, they directly lead to ozone depletion: a thinning of
the ozone layer over some areas of the world.
Ozone-depleting substances include chlorofluorocarbons
(CFCs), which were once extensively used as propellants in
spray cans and as refrigerants and solvents. Many coun-
tries, including the United States, are phasing out the pro-
duction and use of CFCs and other ozone-depleting
substances. Because many of these substances persist in air
for a very long time, however, the ozone layer will take
years to recover, even after these chemicals are no longer
released.
Ground-based measurement networks and instruments on
board aircraft, balloons, and satellites are used to monitor
both the thickness of the ozone layer and concentrations
of ozone-depleting substances in the troposphere and in
the stratosphere.
KEY POINTS
Stratospheric ozone over North America decreased
through the 1980s and early 1990s, but has started
to recover. Before the late 1970s, there was little
change, beyond natural variations, in the thickness
of the ozone layer over North America. Since then,
the thickness of the ozone layer decreased, reach-
ing its lowest level in 1993 (see graphic), with no
further decline occurring in more recent years. v
While the ozone layer has begun to recover, ozone^v
levels over North America during 2002 to 2005
were still 3 percent lower, on average, than those
observed 20 years earlier.
Tropospheric concentrations of total ozone-
depleting substances have been slowly declining.
Between 1995 and 2006, total ozone-depleting sub-
stances in the troposphere have declined 12 percent,
and this decline has contributed to the recent recov-
ery in stratospheric ozone levels. The trends for indi-
vidual ozone-depleting substances vary. Tropospheric
concentrations of many ozone-depleting substances
have declined since the early 1990s, but concentra-
tions of halons (fire extinguishing agents) and
hydrochlorofluorocarbons (HCFCs), a class of chemi-
cals being used to replace CFCs, increased.
Total Ozone Levels Over North America,
1964-2006
— 2
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GREENHOUSE GASES
Some gases in the atmosphere
trap part of the Earth's outgoing
energy, which causes the atmos-
phere to retain heat and affect
climate. These gases are called greenhouse gases, and
they include carbon dioxide, methane, nitrous oxide, and
certain man-made chemicals. Some greenhouse gases
occur naturally, while emissions due to human activities,
such as electricity production and transportation, add to
the natural concentrations in the atmosphere.
Greenhouse gases are important to track because
increased concentrations due to human activity cause the
atmosphere to retain heat which, in turn, is affecting
various aspects of climate, such as temperature, evapora-
tion, and precipitation. Natural phenomena, like volcanic
activity and variations in the sun's output, and other
human activities, such as land use changes, also affect cli-
mate. Human health, agriculture, water resources, forests,
wildlife, and coastal areas all can be affected by climate
change.
National trends in green-
house gases are character-
ized by tracking emissions
of these gases from human
activities and concentrations
of these gases in the air.
Hi
KEY POINTS
Global atmospheric concentrations of several
important greenhouse gases have risen substantial-
ly over the past 100 years. Measurements of gases
trapped historically in Antarctic ice confirm that the
current global atmospheric concentrations of carbon
dioxide (see graphic) and methane are unprecedented
over the past 650,000 years, even after accounting for
natural fluctuations. Concentrations of nitrous oxide
are 18 percent higher than pre-industrial levels; and
concentrations of certain synthetic chemicals were
essentially zero a few decades ago, but increased
rapidly between 1980 and 2006.
\
Between 1990 and 2005, U.S. greenhouse gas emis-
sions from human activities rose 16 percent; the pri-
mary source of these emissions was fossil fuel
combustion. Carbon dioxide, widely reported as the
most important greenhouse gas, makes up most of this
increase. Energy use, primarily electricity generation
and transportation, accounted for approximately 85
percent of the U.S. greenhouse gas emissions in 2005.
While trends in U.S. emissions and global atmos-
pheric concentrations of greenhouse gases are
based on robust data, gaps remain. For both emis-
sions and concentrations, trends have been quantified
for several of the most important greenhouse gases,
but not for every greenhouse gas.
Global Atmospheric Concentrations of Carbon Dioxide (CO2) Over Geological Time and in Recent Years
The concentration data shown are reported in multiple scientific publications. Complete citations for these peer-reviewed publications are provided in
the 2008 Report on the Environment.
Chapter 1 Air
8
Greenhouse Cases
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INDOOR AIR
Many substances affect the qual-
ity of air inside homes, schools,
workplaces, and other buildings.
Some of these contaminants
come from outdoor air and building materials; others are
produced by indoor activities such as cooking, smoking,
and using cleaning materials. Natural substances, such as
mold, can also affect indoor air quality.
Indoor air quality is important because Americans, on
average, spend most of their time indoors. In addition,
the indoor concentrations of some pollutants can exceed
levels typically found outdoors. Health effects associated
with indoor air pollutants include irritation of the eyes,
nose, and throat; headaches, dizziness, and fatigue; res-
piratory diseases; heart disease; and cancer.
National indicators are available for two harmful sub-
stances found in indoor air: radon and environmental
tobacco smoke. Radon is a naturally occurring radioac-
tive gas found underground. It can seep into buildings
through cracks in floors and walls, and is a risk factor for
lung cancer. For homes with radon levels above EPA's
radon action level, EPA recommends that occupants take
action to protect their health—for example, by installing
a mitigation system to reduce radon levels.
Environmental tobacco smoke is associated with numer-
ous health effects, including coughing, heart disease,
and lung cancer. Children are at particular risk from
exposure to environmental tobacco smoke because they
are still developing physically.
KEY POINTS
Between 1990 and 2006, both the number of
homes with radon mitigation systems and the num-
ber of homes needing mitigation increased. Homes
with mitigation systems rose from 1 75,000 to 714,000,
and homes needing mitigation increased from 6.4 mil-
lion to 7.8 million due in part to an increase in housing
stock, particularly in areas with the highest radon
potential (see graphic). More than 90 percent of the
nation's homes with indoor radon levels at or
EPA's action level do not have mitigation systems,
though some of these homes have been built with
new, radon-resistant construction features to reduce
radon exposures.
Over the past decade, exposure to environmental
tobacco smoke among nonsmokers decreased con-
siderably. All population groups, regardless of age, sex,
or ethnicity, experienced this decrease, which was likely
due to behavior changes such as reduced smoking and
smoking restrictions in some public places. Exposure to
environmental tobacco smoke is measured by blood
levels of cotinine, a substance produced in the body
when a person is exposed to nicotine. Among non-
smokers, children, on average, have more than twice
the level of blood cotinine as adults.
National indicators currently are not available for
a broader range of pollutants and substances
found in indoor air. Scientists have studied numer-
ous other indoor air quality issues, but the available
information does not track trends over time or across
the entire nation.
Radon in U.S. Homes, 1990-2006
Homes above EPA s radon action eve
Homes with radon mitigation systems
Source: U.S. Environmental Protection Agency, 1992, 2007
Chapter 1 Air
9
Indoor Air
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WATER
Fresh Surface Waters
Ground Water
Wetlands
Coastal Waters
Drinking Water
Recreational Waters
rom swiftly flowing streams to slow-moving
water underground, the nation's water
resources are integral to life. Water resources
encompass water bodies (such as coastal waters,
lakes, streams, ground water, and wetlands) and
their associated ecosystems. They sustain a multi-
tude of plant and animal species and provide for
drinking water, irrigation, fishing, recreation, and
many other needs.
The ability of water resources to support these
functions depends on their extent and condition.
The extent of a water resource refers to its depth,
flow, volume, and area. Condition reflects the abili-
ty of a water resource to sustain ecological needs
and human uses. The extent and condition of
water resources can affect the health and well-
being of people, ecosystems, and critical environ-
mental processes.
In addition, because water is constantly cycling
above and below the surface of the Earth, there are
many connections between water resources and
other parts of the environment. For example, fertil-
izers and pesticides used on land can leach into
underground or surface water supplies. Also, chem-
icals released into the air can be deposited, via rain
or snow, into a lake or stream.
A variety of methods are used to collect data on
water resources, including targeted monitoring of
specific water resources and select sampling of
locations deemed to be representative of a larger
area. One of the challenges in assessing the extent
and condition of water resources is that a single
data collection method is rarely perfect for every
situation. This chapter provides an overview of
national-level trends where nationally consistent
data are available, but it does not describe the
extent or condition of local water bodies or the full
range of variations and extremes that occur within
individual water bodies.
Consumable Fish and
Shellfish
Chapter 2: Water
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FRESH SURFACE WATERS
Lakes, ponds, rivers, and streams
sustain ecological systems and
provide habitat for many plants
and animals. They provide
drinking water for people and support agriculture, indus-
try, hydropower, recreation, and other uses. Both natural
processes and human activities influence the condition
of these waters. For example, discharges of industrial
contaminants, agricultural and stormwater runoff, air
pollutants deposited into water, and invasive species can
all affect water bodies.
A variety of biological, physical, and chemical characteris-
tics are used to assess the condition of fresh surface
waters. An important biological characteristic is the pres-
ence and diversity of bottom-dwelling (benthic) macroin-
vertebrate communities, such as insect larvae, mollusks,
and worms. Some species of macroinvertebrates are
more sensitive than others to disturbances in their habitat,
such as pollution.
Examples of physical characteristics are depth and flow.
Major changes in stream flows can affect plant and animal
species that have adapted to particular seasonal fluctua-
tions in flow, such as those that require a period of low or
no stream flow in their habitat at a certain time of year.
Key chemical characteristics include acidity and dissolved
oxygen. Acidity in soils, lakes, and streams can harm
aquatic species and ecosystems. Low dissolved oxygen
content can also be harmful. Excess concentrations of
the nutrients nitrogen and phosphorus (from sewage or
agricultural runoff, for instance) can cause algae to
bloom in water. As the algae die and decompose, they
deplete the oxygen in the water needed by fish and
other organisms.
KEY POINTS
In about 42 percent of wadeable stream miles,
benthic macroinvertebrate communities show
substantial disturbance; about 28 percent show
little disturbance (see graphic). Low biological diversi
ty potentially indicates substantial pollution and higher
disturbance. By contrast, communities that are biologi-
cally diverse and include many pollution-sensitive
species likely indicate that a stream is less disturbed-
Wadeable streams are streams and rivers shallow
enough to sample without boats.
Since 1960, more than half of the rivers and
streams measured nationwide have shown
major changes in the volume of high and low
flows over time. In largely arid grasslands and
shrublands, the percentage of streams with no-flow
periods decreased slightly between 1960 and 2006,
along with the average length of no-flow periods.
Fresh surface waters show a mixed picture of
chemical condition. Acidity has decreased since the
early 1990s in lakes and streams in most regions sen-
sitive to acid rain, although one region showed little
change. Approximately 30 percent of the nation's
wadeable stream miles contain high nitrogen and
phosphorus concentrations. Over the last several
decades, nitrate loads increased in the Mississippi
River. Phosphorus loads decreased in the St.
Lawrence and Susquehanna Rivers, but showed no
clear trend in the Mississippi or Columbia rivers.
The extent of surface waters and many key stres-
sors are not currently tracked by national indica-
tors. Key stressors include pollution from various
sources and toxic contaminants in sediments, which
can impact water quality and potentially enter the
aquatic food web.
Benthic Community Condition in Wadeable Streams,
2000-2004
Not assessed/no data
Moderately
disturbed
Data gathered from 2000 to 2004 in the lower 48 states.
Categories based on the number and diversity of benthic species pres-
ent, with "least disturbed" being the most diverse. Graphic shows the
percent of stream miles in each category.
Source: U.S. Environmental Protection Agency, 2006
Most
disturbed
Chapter 2 • Water
11
Fresh Surface Waters
-------
GROUND WATER
1
More than 1 million cubic miles
of fresh water lies underground,
stored in cracks and pores below
the Earth's surface. The vast
majority of the world's fresh water available for human use
is ground water, which has 30 times the volume of the
world's fresh surface waters. Many parts of the country
rely heavily on ground water for important needs such as
drinking water, irrigation, industry, and livestock.
Some ecological systems also depend on ground water.
For example, many fish species depend on spring-fed
waters for their habitat or spawning grounds. Springs
occur when a body of ground water reaches the Earth's
surface. By some estimates, ground water feeds about
40 percent of total national stream flow, and the per-
centage could be much higher in arid areas.
Human activities and natural factors can affect both the
extent and condition of ground water. Pesticides, fertiliz-
ers, and wastes, as well as natural substances like arsenic,
can contaminate ground water. For example, fertilizers
and animal wastes used on land can release nutrients such
as nitrate, which can seep into ground water.
Withdrawing too much ground water from a source can
reduce the water depth in streams and lakes, affecting
vegetation and wildlife habitat. It can also cause land to
subside and sinkholes to form. Once depleted, some deep
aquifers (underground geological formations containing
water) can take thousands of years to recharge, affecting
the supply of ground water available for future needs.
KEY POINTS
About 60 percent of shallow wells tested in agri-
cultural areas contained pesticide compounds.
Approximately 1 percent of the shallow wells tested had
concentrations of pesticides above levels considered safe
for human health.
In about 21 percent of shallow wells, average
nitrate concentrations exceeded the federal
drinking water standard and were much higher
than the levels generally found in areas with
little human influence (see graphic). Public water
systems must test for nitrate and treat the water if
levels exceed federal health-based standards.
The data in this report do not provide information
about the condition of deeper aquifers, which are
more likely to be used for public water supplies.
These data only characterize the uppermost layers
of shallow aquifers typically used by private wells.
There are no national treatment or monitoring
requirements for private wells; however, owners
should test their water periodically to identify
possible health risks.
There are no consistent national indicators for
many aspects of ground water condition or
extent. These aspects include the presence of
chemicals other than nitrates and pesticides in agri-
cultural areas and the condition of ground water in
predominantly non-agricultural areas, including
urban areas. Localized events, such as chemical spills
or leaks from underground storage tanks, can affect
ground water in urban areas; such events are difficult
to measure at the national level.
Nitrate Concentrations in Shallow Ground Water
in Agricultural Watersheds, 1992-2003
6 to
<10mg/l
13.5%
v 1 to <2 mg/L
7.7%
Data gathered in a survey of 1,423 wells in the lower 48 states from
1992 to 2003. Graphic shows percent of wells in each category.
The federal drinking water standard for nitrate is 10 milligrams of
nitrate per liter of water (10 mg/L).
Totals do not add up to 100% due to rounding.
Source: U.S. Geological Survey, 2007
Chapter 2 • Water
Ground Water
-------
WETLANDS
Wetlands—areas that are periodi-
cally saturated or covered by
water—are an important ecologi-
cal resource. Wetlands are like
sponges, with a natural ability to store water. They act as
buffers to flooding and erosion, and they improve the
quality of water by filtering out contaminants. Wetlands
also provide food and habitat for many plants and ani-
mals, including rare and endangered species. In addition,
they support activities such as commercial fishing and
recreation.
Both losses and gains can occur in wetland extent. Natural
forces and human activities (such as hurricanes, sea level
change, and certain agricultural and forestry practices) can
affect wetlands through increased erosion and sedimenta-
tion. Draining or filling wetlands for agriculture or other
development is the main cause of wetland loss. Gains can
occur when wetlands are created or restored.
Changes in the extent or type of wetlands can have
major ecological impacts. For example, the conversion of
a forested wetland to shrub
vegetation can change
habitat types and alter
the structure of plant
and animal communi-
ties present. Such a
conversion can occur
through natural
changes in plant com-
munities or by clearing
trees from a forested
wetland.
KEY POINTS
The overall extent of wetlands in the lower 48
states declined over the past 50 years. The rate of
loss has slowed over time, however, and the most
recent data show a net gain in wetlands acreage
nationwide (see graphic). Gains and losses vary by
wetland type. Freshwater ponds account for most of
the recent gains in wetland acreage. These ponds
do not perform the same range and type of envi-
ronmental functions as other types of wetlands that
have been lost.
These data do not evaluate wetland quality or
condition. Wetland condition is difficult to charac-
terize fully, and there is no national indicator to
measure it directly. This is partly because each
wetland has unique characteristics, such as the
movement and abundance of water, the minerals
in the underlying soil, and the combinations of
plant and animal species present.
National data do not capture locations or patterns
of wetland change. Both are important for under-
standing condition—for example, whether large
wetlands are being left intact or are being fragmented
into smaller pieces that are less connected and, there-
fore, less able to perform their ecological functions.
Average Annual Change in Wetland Acreage,
1954-2004
Net change (acres per year)
iuu,uuu •
o-
-300,000-
-58,600
+32,000
-290,000
-458,000
1954-1974 1974-1983 1986-1997
1998-2004
Data gathered in the lower 48 states.
Source: U.S. Fish and Wildlife Service, 2006
Chapter 2 Water
13
Wetlands
-------
COASTAL WATERS
Coastal waters—the interface
between terrestrial environments
and the open ocean—encom-
pass many unique habitats such
as estuaries, coastal wetlands, seagrass meadows, coral
reefs, and mangrove and kelp forests. These ecologically
rich areas support waterfowl, fish, marine mammals, and
many other organisms.
Human activities and natural factors can affect the condi-
tion of coastal waters. Sewage overflow, agricultural
runoff, storms, erosion, and sedimentation can all
increase the amount of nutrients (such as nitrogen and
phosphorus) and pathogens (disease-causing organisms)
in coastal waters. Chemical contamination from industri-
al activities, electricity generation, and other sources are
also concerns, as are invasive species and overharvesting
of fish and other marine species.
Organisms that live in and on the ocean floor (benthic
organisms) are a key measure of coastal water condition
because these organisms are sensitive to pollution. One
important group of benthic organisms, known as benth-
ic macroinvertebrates, includes worms, clams, crabs, and
lobsters.
Scientists monitor several interlinked characteristics of
water quality in coastal areas: nutrients, chlorophyll-o,
dissolved oxygen, and water clarity. Plants need nutrients
to grow, but in excess, nutrients fuel the growth of
algae. High levels of chlorophyll-o indicate overproduc-
tion of algae. Too much algae leads to low levels of dis-
solved oxygen in the water and decreased water clarity.
The resulting lack of oxygen and sunlight can harm
plant and animal life.
Scientists also monitor plants that grow under water in
coastal areas, known as submerged aquatic vegetation
(SAV). Like all plants, SAV needs sunlight to grow and
survive. Its growth can be affected by excess nutrients,
as well as suspended sediments (loose particles of clay
and silt in the water), which can block sunlight from
reaching the plants.
KEY
Coasti
POINTS
Coastal benthic communities in 70 percent of the
areas sampled showed little evidence of distur-
bance (see graphic). The benthic communities in these
areas showed high biological diversity and the presence
of pollution-sensitive species, likely indicating that the
waters were relatively unpolluted.
SAV plays an important ecological role, for
example, in the Chesapeake Bay, where SAV
increased from 41,000 to 59,000 acres from
1978 to 2006. However, current acreage is still less
than half of the historical coverage (from the mid-
1930s). The extent of these plants is important
because the vegetation provides food and habitat for
many organisms, adds oxygen to the water, filters
sediments, inhibits wave action that erodes shore-
lines, and absorbs excess nutrients.
Elevated levels of nutrients and chlorophyll-o are
present in slightly less than 10 percent of the
nation's coastal waters. However, in areas such as
the Gulf of Mexico dead zone and Long Island
Sound, substantial areas of hypoxia (when dissolved
oxygen is below levels necessary to sustain most
animal life) are present.
There are no national indicators for the extent of
coastal waters and many aspects of their condition.
For example, there are no national indicators for SAV,
invasive species, harmful algal blooms, condition of
coral reefs, or status of coastal fish and shellfish com-
munities.
Benthic Community Condition in Estuarine Waters,
1997-2000
Moderately
disturbed
Data gathered in the lower 48 states and Puerto Rico from 1997 to 2000.
Categories based on the number and diversity of benthic species present,
with "least disturbed" being the most diverse. Graphic shows the percent
of estuarine area in each category. Estuarine areas are where a freshwater
stream or river meets the ocean.
Source: U.S. Environmental Protection Agency, 2004
Chapter 2 • Water
14
Coastal Waters
-------
'
DRINKING WATER
Virtually all drinking water in the
United States comes from fresh
surface water and ground water.
These source waters can contain
industrial, domestic, and agricultural contaminants, as well
as naturally occurring contaminants such as arsenic and
radionuclides. Also, some contaminants, such as lead from
corroded pipes, can enter drinking water between the
treatment plant and the tap. If these contaminants are
present in drinking water at sufficient levels, they can lead
to adverse health effects, including gastrointestinal illness-
es, nervous system and reproductive effects, and chronic
diseases such as cancer.
To protect public health, EPA sets federal health-based
standards for drinking water for public water systems.
Public water systems include community water systems—
systems that supply drinking water to 25 or more of the
same people year-round in their residences. Community
water systems serve more than 286 million people, or
about 95 percent of the U.S. population.
Public water systems must test for regulated contaminants
and treat the water, if needed, to meet the federal stan-
dards. Disinfection of drinking water effectively protects
against the risk of waterborne diseases such as typhoid,
cholera, and hepatitis.
Filtration, required for
most public water sys-
tems that use surface
water, provides addi-
tional protection U*fl»J&
against microbial
contaminants.
•
KEY POINTS
In 2007, 92 percent of community water system
customers (262 million people) were served by
facilities for which states reported no violations of
EPA's health-based drinking water standards (see
graphic). Approximately 24 million people in 2007 were
served by systems for which states did report viola-
tions of these standards. A portion, but not all, of
these people might have been exposed to contami-
nants in drinking water at levels above standards.
Most of these violations involved rules addressing
microbial contaminants or disinfection byproducts
(chemicals that can form when disinfectants, such as
chlorine, react with naturally occurring materials in
water). The level of health risk associated with viola-
tions varies, depending partly on which contami-^v
nants were involved, the extent to which a standard
was exceeded, the extent to which the distribution
system was affected, and how long the violation
lasted. Microbial violations, in particular, can be
short term.
These data address drinking water from com-
munity water systems only. They do not address
the quality of drinking water that people get from
nonpublic supplies (such as private wells and
untreated surface water sources), from public
water systems serving transient populations (such
as roadside rest stops and campgrounds), or from
nonresidential users (such as some workplaces and
schools). National data are not available for bot-
tled water, which is regulated by the Food and
Drug Administration.
Health effects that could be caused by contami-
nants in drinking water are not currently tracked by
national indicators. For example, no national indicator
is available for disease occurrence or outbreaks caused
by harmful microorganisms in drinking water.
Population Served by Community Water Systems With
No Reported Violations of EPA Health-Based Standards,
1993-2007
100
1 =
S= O
8 E
'Several new standards went into effect after December 31, 2001. For the
years 2002 through 2007, the darker segment at the top of each column
shows the additional population that would have been served by systems
with no reported violations if the new standards had not gone into effect.
Data are presented by EPA fiscal year (October 1-September 30).
Source: U.S. Environmental Protection Agency, 2007
Chapter 2 • Water
15
Drinking Water
-------
RECREATIONAL WATERS
People enjoy many recreational
activities on the nation's rivers,
lakes, and coastal waters. Several
characteristics determine whether
these waters are suitable for recreation. For example, the
levels of chemical contaminants and disease-causing
microorganisms in water affect whether the water is suit-
able for swimming, boating, and other contact activities.
KEY POINTS
While information exists about many individual
water bodies, consistent national indicators for
recreational waters are not yet available. Many
states and localities collect information about individ-
ual water bodies in their region. States also monitor
coastal beaches for levels of certain disease-causing
bacteria and report the results to EPA. However, differ-
ent states monitor in different ways (for example, by
using different methods or monitoring more or less
The condition of ecosystems and the wildlife within
them, which support recreational activities such as fish-
ing and bird watching, is also important. While many of
these characteristics can be measured at a local level,
there are several barriers to compiling these data into
national indicators.
frequently), making it difficult to compile the results
into national indicators.
Improved data collection could lead to suitable
indicators in several areas. For example, with a
comprehensive national system for gathering data,
scientists could develop consistent national indicators
for bacteria levels at beaches.
Chapter 2 Water
16
Recreational Waters
-------
CONSUMABLE FISH AND SHELLFISH
Fish and shellfish are an impor-
tant part of a healthy diet for
many Americans. Some fish and
shellfish from lakes, rivers, estuar-
ies, and deep ocean fisheries, as well as farmed fish and
shellfish, can contain chemicals or disease-causing organ-
isms at levels that can pose human health risks. Sources of
these contaminants include runoff from urban and agricul-
tural areas, pollutants deposited in water from the air, and
direct discharges into water bodies.
Concerns about fish and shellfish safety are higher for peo-
ple who eat a lot of fish and groups of people who are
particularly vulnerable to contaminants that may be
present in fish—such as infants, children, the elderly, and
women who are pregnant or might become pregnant.
Of particular interest in measuring the condition of con-
sumable fish and shellfish are chemicals such as mercury,
polychlorinated biphenyls (PCBs), the pesticide DDT or
dichloro-diphenyl-trichloroethane, and polycyclic aromatic
hydro-carbons (PAHs), which form during the combustion
of oil, gas, and other organic substances. These com-
pounds can persist in sediments for a long time, increasing
their potential for entering the food web and ultimately
concentrating in fish that may be eaten by people and
wildlife.
EY P<
Estuarine sites (sites in areas where a freshwater
stream or river meets the ocean) across the nation
showed varying levels of contamination in fish
tissue. Sixty-three percent of the sites showed low fish
tissue contamination, 15 percent showed moderate
contamination, and 22 percent had high contami-
nation based on health-based consumption guide-
lines (see graphic). PCBs, mercury, DDT, and PAHs
were most often responsible for high contamination
scores. The condition of coastal fish varied greatly
among different areas of the country. The survey
did not include Hawaii, the Caribbean, the Pacific
territories, or Alaska, which is notable because
Alaska produces more than half the nation's
commercial fish. ^s
Lake fish surveys found that several chemicals,
including mercury, dioxins and furans, PCBs, and
DDT, are widely distributed in the nation's lakes
and reservoirs. However, some other chemicals,
including certain pesticides, were detected rarely
or not at all. These data do not consider whether
the detected levels are a health concern, as this por-
tion of the analysis is not yet complete. The surveys
did not include Hawaii, the Caribbean, Alaska, or
the Great Lakes.
While fish consumption advisories provide infor-
mation on fish from many individual water bod-
ies, these advisories cannot be compiled into a
national indicator of fish and shellfish condition.
The states and tribes that issue fish consumption advi-
sories use different ways of monitoring waters and
making advisory decisions, so the information is not
comparable.
There are no consistent national indicators for
disease-causing organisms in fish and shellfish,
or for the biological and chemical condition of
commercially farmed fish and shellfish.
Contaminants in Fish From Estuarine Waters, 1997-2000
At least one
contaminant above
its guideline range
High
22%
Moderate
15%
Low
63%
- All contaminants
below their
guideline ranges
At least one •
contaminant within
its guideline range,
but no exceedances
Data gathered in the lower 48 states from 1997 to 2000.
Categories are based on comparison to EPA's health risk guidelines for fish
consumption. Graphic shows the percent of estuarine sites in each category.
Source: U.S. Environmental Protection Agency, 2004
Chapter 2 • Water
17
Consumable Fish and Shellfish
-------
LAND
Land Cover
Land Use
Chemicals Applied and
Released to Land
Contaminated Lands
and provides food, shelter, fuel, and raw mate-
rials for people, as well as habitat for many
species. It is the source of many resources such
as minerals, timber, and petroleum and helps to fil-
ter the nation's water and break down wastes and
chemicals. While the amount of land in the United
States is relatively constant, how land is used
changes continuously. Changes in land use affect
the distribution and nature of land cover (such as
forests, developed land, and agricultural land) and
the condition of land and its resources.
Land is intricately connected to other environmental
resources and to human health. For example, land
cover affects the energy exchange between the
Earth's surface and atmosphere, which in turn influ-
ences climate and weather. Changes in land cover
can increase or decrease erosion, water runoff, sedi-
mentation, and flooding. Chemicals and wastes can
affect human health and the environment when
they are applied to or disposed of on land.
Many federal agencies with varying responsibilities
collect data on land resources using satellite
imagery, national surveys, and regulatory data.
These data, in general, represent only a small
sample of the total picture of land cover, land use,
waste management and disposal, chemicals used
on land, and land contamination. States also
collect these kinds of data, but differ in their
approaches, making it difficult to compile national
data on land issues.
Chapter 3: Land
-------
LAND COVER
Land cover is the vegetation and
other materials, such as rock, snow,
or pavement, that are present and
visible on land. Satellite data are fre-
quently used to identify land cover types over large areas.
Land cover can be grouped into six major categories: forest
cover, grass cover, shrub cover, developed land, agriculture,
and other (which includes ice/snow, bare rock, and other
types of land cover with limited extent). Land cover differs
from land use. Land cover is physically obvious, while land use
is determined by a government agency or individual
landowner and might not always be visible. Because of these
differences, land cover acreages differ from land use acreages
in the United States.
A number of factors affect land cover, including geology, cli-
mate, population changes, and human activities such as
industrial and urban development, deforestation or reforesta-
tion, water diversion, and road building. The extent and type
of land cover in an area can affect habitat quality and availabil-
ity, species distribution, water quality, climate, and distribution
and movement of chemicals.
KEY POINTS
Forest cover and agriculture are the two most common
types of land cover in the United States. In 2001, of the
approximately 2.3 billion acres of land in the nation, 641
million acres were forest cover, 449 million acres were agri-
culture, 419 million acres were shrub, 291 million acres
were grass, and 103 million acres were developed land.
These estimates were derived from satellite data.
Land cover types vary greatly by region (see graphic).
Forest cover is predominant in the East and Pacific
Northwest, agriculture and grass cover in the Midwest, and
shrub cover in the Southwest.
\
The total amount of forest in the United States
declined over the last century, but has been increasing
in recent years. Regional variations exist. Forest cover has
increased in the Northeast, Mid-Atlantic, and Midwest, and
decreased in the West and Southwest
Comparing and integrating land cover information is
difficult. Different agencies collect data on land cover,
often at varying times and for different purposes. These
agencies also define and classify land cover differently and
at varying levels of detail. The most recent comprehensive
data available are from 2001.
I
Land Cover, 2001
1
Agriculture
Cultivated crops
Pasture/hay
Grass cover
Grassland
Shrub cover
Shrubland
Developed
• High-density (impervious£80%)
Medium-density (impervious 50-79%)
• Low-density (impervious 20-49%)
• Open space (impervious <20%)
Other
D Perennial ice/snow
Barren
Woody wetland
Emergent herbaceous wetland
ores) cover
Deciduous forest
Evergreen forest
Mixed forest
Water
• Open water
Source: U.S. Environmental Protection Agency, 2007
Chapter 3 Land
19
Land Cover
-------
LAND USE
U.S. lands support many uses,
including crop production, tim-
ber production, livestock grazing,
recreation, and residential and
commercial development. Designated through zoning and
other regulations, these uses are often less physically obvi-
ous than land cover. For example, developed land use can
include land that has visibly developed features, such as
asphalt, concrete, and buildings, as well as undeveloped
land designated for residential or transportation use.
Land use can adversely affect numerous aspects of the
environment, including air and water quality, habitat avail-
ability, and species distribution. In some cases, land use can
also have positive environmental effects, such as when
communities restore habitats or clean up and redevelop
contaminated lands.
KEY POINTS
Widespread land uses in the United States include
grazing, timberland, and food crop production. As of
2003, of the approximately 2.3 billion acres of land in
the nation, as many as 721 million acres were used for
grazing, 504 million acres were classified as potentially
productive forest (known as timberland), 374 million
acres were used for food crop production, and 108 mil-
lion acres were used for development. These data are
based on aerial photo interpretation and ground surveys.
Land use patterns vary greatly by region of the
country. More than three-quarters of the nation's
grazing land is in the West, while much of the timber-
land is concentrated in the East and Southeast.
The amount of land used for crop production and
pasture has declined since 1982, while the amount
of developed land has increased and timberland has
remained constant. Conversions of forest land, crop-
land, and pastureland have contributed to the increases
in developed land. Additionally, highly erodable crop-
land has been removed from production.
Between 1982 and 2002, the amount of developed
land in the United States increased at nearly twice
the rate of the population (see graphic). The amount
of developed land grew by about 47 percent, while the
population grew by just over 24 percent. Population
and development trends varied in different parts of the
country. For example, in the West, the amount of land
developed since 1982 closely matched population
growth, while in the Northeast, the amount of devel-
oped land increased at more than three times the rate
of population growth.
The data to track land use trends are limited and
derived from many sources, which inhibits the abili-
ty to track changes over time. Various agencies col-
lect land use data, often at different times and for
different purposes. Classifications of land use can also
vary, making it difficult to integrate and compare data.
Change in Population and Developed Land,
1982-2002
14
12-
10-
1982-
1987
1987-
1992
1992-
1997
1997-
2002
Change in population
Change in acreage
of developed land
Data gathered in the lower 48 states
and Hawaii, except for 1997-2002,
when data on developed land were
not available for Hawaii.
Source: U.S. Census Bureau, 1996,2002, 2006; U.S. Department
of Agriculture Natural Resources Conservation Service, 2000,
2004
Chapter 3 Land
20
Land Use
-------
WASTES AND THE ENVIRONMENT
The amount, composition, and
•1 management of wastes provide
insight into the nation's efficiency
in using materials and resources.
Such information also can be useful in understanding the
effects of wastes on human health and the environment.
The type and amount of waste produced in the United
States varies and can depend on the size and activities of
an organization. For example, households primarily pro-
duce municipal solid waste (paper, packaging, yard trim-
mings, and other materials) and discard some products
with potentially hazardous ingredients and small amounts
of hazardous waste. Commercial and manufacturing enti-
ties and institutions produce municipal solid waste, indus-
trial waste, and larger quantities of hazardous waste.
Hazardous wastes have properties (toxicity corrosiveness,
ignitability reactivity) that make them potentially harmful
to human health or the environment.
Activities such as agriculture, construction/demolition,
mining, and other resource extraction and industrial
processes generate large quantities of other types of
waste. Presently, however, the United States regularly col-
lects information on only municipal solid waste and haz-
ardous waste. These two types of waste make up a small
fraction of all of the waste generated in the country.
Once wastes are generated, they must be managed—col-
lected, transported, stored, reused, recycled, processed or
treated, or disposed of. Because wastes can contain haz-
ardous chemicals, their generation and management have
the potential to contaminate land, air, or water; compro-
mise their use; affect human health; or impact ecological
condition. For example, the decomposition of certain kinds
of wastes in landfills is a major source of methane. In con-
trast, industry has taken steps to reduce certain high-priori-
ty chemicals (documented contaminants of air, water, land,
plants, and animals) found in waste in recent years.
KEY POINTS
Since 1990, the per capita municipal solid waste
generation rate has remained stable at four-and-
one-half pounds per person per day. As the U.S.
population has increased, however, the nation has
steadily generated more municipal solid waste.
Generation increased from 88 million tons in 1960 to
251 million tons in 2006.
Hazardous waste generation has declined. Hazardous
waste generation dropped from roughly 36 million tons
in 1999 to 28 million tons in 2005. Recycling or com-
posting of municipal solid waste increased from 6 per-
cent to 33 percent since 1960 (see graphic). Hazardous
waste recycling rose only slightly between 1999 and
2005 and remains at less than 10 percent.
Most waste is still disposed of on land. In 2006, 55
percent of municipal solid waste was disposed of in
landfills, compared to 94 percent in 1960 (see graph-
ic). Of the hazardous waste disposed of on land in
2005, 90 percent was injected deep into the ground in
permitted wells, and the remaining 10 percent was
treated and disposed of in a manner to minimize risk to
human health and the environment.
Information about many types of waste is not cur-
rently available at the national level. Also, data are
lacking about exposure and the effects of waste and
management practices on human health and the envi-
ronment. The potential effects associated with waste
vary widely and are influenced by the substances or
chemicals found in waste and how they are managed.
Municipal Solid Waste Management, 1960-2006
300
_ 25°
"c/r
3 200
£=
O
| 150
CD
« 100
CO
50
0
Recovery for composting^
Combustion with energy recovery.
Landfill or other disposal
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Source: U.S. Environmental Protection Agency, 2007
Chapter 3 Land
21
Wastes and the Environment
-------
CHEMICALS APPLIED AND RELEASED TO LAND
Chemicals are commonly used
in manufacturing, in food and
consumer products, and in
efforts to manage diseases. They
can be intentionally applied to land for purposes of
increasing crop yields and controlling pests, or in some
cases, accidentally spilled on land. Some chemicals also
occur naturally or can enter the environment through
acts of nature, such as volcanoes and hurricanes.
Chemicals released or applied to the environment can
pose a range of challenges to human health and the
environment. Some chemicals break down quickly in the
environment, while others, such as persistent, bioaccu-
mulative, and toxic (PBT) chemicals, persist for long peri-
ods of time and can accumulate in the food web.
KEY POINTS
Some chemicals can lead to health problems if people
receive sufficient doses. For many other chemicals,
though, the possible health effects are not yet well
known. The effects of
long-term exposure
to chemicals are
often un-
known. In
addition,
some chemi-
cals can harm
ecosystems,
such as when
excess fertilizers are
carried in runoff, which can affect water quality and
aquatic life.
The amount of certain toxic chemicals in industri-
al waste materials decreased by more than 4 bil-
lion pounds (16 percent) between 1998 and 2005
(see graphic). In 2005, the United States handled
1.1 billion pounds of PBT chemicals in industrial waste,
along with 24 billion pounds of other toxic chemicals
(shown in graphic) that are subject to reporting to EPA
under the Toxics Release Inventory (TRI) program. The
metal mining industry has accounted for 35 percent of
the total TRI chemicals in production-related wastes
released to the environment since 1998.
Over the past 45 years, the use of fertilizers,
including nitrogen, phosphate, and potash, has
increased nearly three-fold. The combined use of
these three chemicals rose from 46 pounds per acre
per year in 1960 to 138 pounds per acre in 2005.
Nitrogen accounted for the steepest increase. While
fertilizers are not inherently harmful, they have the
potential to contaminate ground and surface water
when applied improperly or in excessive quantities.
In annual surveys conducted since 1994, 42 to 71
percent of food samples have shown detectable
amounts of pesticide residue. A small fraction of
samples (approximately 1 out of every 500) had pesti-
cides at concentrations that exceeded tolerance levels
designed to protect human health. Foods tested include
fruits, vegetables, grains, meat, and dairy products.
Data about chemicals used on land are limited. Some
data are available on pesticide and fertilizer use on agri-
cultural lands. Agencies collect national information on
only a fraction of all chemicals used in the United
States, however. Consistent national indicators are lack-
ing regarding when, where, and how frequently chemi-
cals are applied to land and the potential impact when
they contain toxic ingredients.
Disposition of Toxics Release Inventory (TRI)
Chemical Waste, 1998-2005
Is (billion pounds)
Ol O Ol O t
f ,0
5 5
0
This gr
chemic
accum
report!
in 200'
the 20(
Source
Agency
6.8
8.3
3.6
9.2
6.9
9.1
3.4
8.6
6.3
13.0
3.7
9.6
5.2
8.6
3.5
8.9
4.4
8.0
3.7
9.0
1998 1999 2000 2001 2002
aph does not include a subset ol
als designated as persistent, bio
jlative, and toxic (PBT) because
ig requirements for PBTs change
. For a graph of PBT trends, see
18 Report on the Environment.
: U.S. Environmental Protection
2007
4.0
8.2
3.3
8.3
3.8
9.0
3.2
8.5
3.8
8.6
3.0
8.2
2003 2004 2005
d
n Released
n Treated
n Combusted
for energy
recovery
n Recycled
Chapter 3 Land
22
Chemicals Applied and Released to Land
-------
CONTAMINATED LANDS
Contaminated lands range from
abandoned properties in inner
cities to large areas of land once
used for industrial or mining
activities. Improper handling or disposal of toxic and
hazardous materials and wastes, improper application of
chemicals to land, deposition of toxic substances on land
via winds or water, and accidental spills can all contami-
nate land. Except for spills and natural events, most land
contamination is the result of historical activities that are
no longer practiced.
The Comprehensive Environmental Response, Compen-
sation, and Liability Act, also known as Superfund, and
the Resource Conservation and Recovery Act (RCRA) are
two of the major federal laws governing contaminated
lands to protect human health and the environment.
The most toxic abandoned waste sites in the nation are
listed on the Superfund National Priorities List (NPL).
High-priority facilities subject to cleanup under RCRA are
included in the RCRA Cleanup Baseline.
Completing cleanups at these complex sites can take
years and even decades; therefore, EPA tracks whether
people are exposed to contamination above levels of
concern, and whether contaminated ground water is
spreading above levels of concern.
KEY POINTS
Between 2002 and 2007, the percentage of Super-
fund NPL sites where human exposure to contami-
nation was under control (that is, unlikely to be
occurring) remained relatively constant at 82 per-
cent (see graphic). The other 18 percent of sites either
had documented exposure or had not been
classified yet.
Between 2000 and 2007, the percentage of RCRA
Cleanup Baseline sites where human exposure to
contamination was demonstrated to be under
control increased from 37 to 93 percent. This
increase was due to completion of site investigations,
actions taken to prevent exposure to contamination,
and further site cleanup.
Sites where contaminated ground water was
demonstrated not to be spreading above lev-
els of concern increased from 61 to 70 percent
of Superfund NPL sites (2002-2007) and from
32 to 79 percent of RCRA Cleanup Baseline
facilities (2000-2007). The increases are due to
completion of site investigations, actions taken to
mitigate the spread of contaminated ground
water, and further site cleanup.
The total number and extent of contaminated
sites nationwide is not known, nor are their specific
effects on human health and the environment.
Although EPA tracks the most contaminated sites
through the RCRA Cleanup Baseline and Superfund
NPL, these sites do not represent the full extent of con-
taminated lands in the United States. Many other sites
managed by local, state, and other federal authorities
are not inventoried at the national level.
Human Exposure to Contamination
at Superfund National Priorities List (NPL)
Sites, 2002-2007
2,000
1,500
. 1,000
500
1,494 1.494 1.494
175
120
1,199
(80%
of
total)
158
109
1,227
(82%
of
total)
146
1U1
1,247
(83%
of
total)
1,544
161
14R
1,235
(80%
of
total)
1,554 1,554
172
113
1,269
(82%
of
total)
163
109
1,282
(82%
of
total)
2002 2003 2004 2005 2006 2007
"Exposure likely" means that there is a reasonable expectation that
humans are exposed to contamination above health-based standards.
Data are presented by EPA fiscal year (October 1-September 30).
Source: U.S. Environmental Protection Agency, 2005, 2006, 2007
Chapter 3 Land
23
Contaminated Lands
-------
HUMAN EXPOSURE
AND HEALTH
Exposure to Environmental
Contaminants
Health Status
Diseases and Health
Conditions
any factors can influence human health,
including exposure to environmental con-
taminants. People can be exposed to envi-
ronmental contaminants in a variety of ways, and
many contaminants are known or suspected of
causing human disease. The relationships among
environmental contaminants, exposure, and human
disease are complex, however. Despite these com-
plexities, studying overall patterns of disease or
exposure helps determine where further study or
public health interventions could be needed.
For people to experience adverse health effects from
exposure to an environmental contaminant, various
events must occur. First, a contaminant released
from its source requires some sort of contact (via air,
water, or land) with a person and then must enter
the body through inhalation, ingestion, or skin con-
tact. Additionally, a contaminant needs to be pres-
ent within the body at sufficient doses to ultimately
result in a health effect. Understanding the connec-
tions between environmental exposure and adverse
health effects is particularly challenging because
many risk factors other than the environment—
including genetics, personal behavior, and health
care—also affect health.
Exposure and health data are drawn from many
sources. These include records of vital statistics, such
as births and deaths; surveys and questionnaires;
and surveillance activities, such as cancer registries
and other systems. As used in this report, these data
are representative of the national population. They
are not based on data from targeted populations or
tied to specific exposures or releases.
At present, trends in national-level exposure and
health indicators cannot be linked to trends in
environmental conditions described in other parts
of this report, or to predict cause-and-effect rela-
tionships between environmental contaminant
exposure and an adverse health effect. Instead,
these national-level data can help researchers
track overall trends in population exposure,
health, and disease, including trends across
different age, gender, race, and ethnic groups.
Chapter 4: Human Exposure and Health 24
-------
EXPOSURE TO ENVIRONMENTAL CONTAMINANTS
People can be exposed to many
different contaminants in the
environment. Although research-
ers can measure the levels of
contaminants in air, water, and land, these measurements
alone cannot reveal whether or how much of those chemi-
cals have contacted or entered people's bodies.
Biomonitoring is used to measure internal body levels of
contaminants (or substances produced when the body
interacts with contaminants) in human blood, urine,
or tissues. This type of direct measure offers more informa-
tion about the extent of exposure to people than environ-
mental levels alone.
Biomonitoring data can help track levels of people's expo-
sure to environmental contaminants, but cannot be used
to determine how people might have been exposed to a
contaminant, or in most cases whether they will become
sick. Currently, biomonitoring techniques exist for only a
subset of the many environmental contaminants.
Blood lead levels show a steady decline since the
1980s. Lead can harm the brain, nervous system, and
other organ systems. Children aged 1 to 5 years have
the greatest health risk from lead exposure because
their systems are still developing. Between 1999 and
2002,1.6 percent of children aged 1 to 5 years had
elevated blood lead levels, decreasing from 88 percent
in the late 1970s. The Centers for Disease Control and
Prevention define elevated blood lead levels as 10
micrograms of lead per deciliter of blood.
About 6 percent of women of child bearing
age had at least 5.8 parts per billion of mercury
in their blood from 1999 to 2002. EPA has deter-
mined that children born to women with blood
concentrations of mercury above 5.8 parts per bil-
lion are at increased risk of adverse health effects.
Exposure to environmental tobacco smoke
among nonsmokers decreased considerably in
the last decade (see graphic). Nonsmokers who
are exposed to environmental tobacco smoke can
have elevated levels of cotinine in their blood.
Cotinine is a substance that forms in the body
following exposure to nicotine.
Baseline measurements of exposure are also
available for other biomonitoring indicators.
These measurements can be used in the future to
track possible trends. Baseline measurements are
available for cadmium, a metal that enters the
environment through natural and man-made
processes; phthalates, used to soften and increase
flexibility of plastics and vinyl; persistent organic
pollutants (POPs); man-made chemicals (such as
polychlorinated biphenyls, dioxins, and furans)
that can remain in the environment for years or
decades; and pesticides, including chemicals to control
weeds, insects, and other organisms.
Biomonitoring data currently have limitations as
indicators of exposure. Because biomonitoring data
do not include the sources of exposure, these indica-
tors alone do not indicate whether measured levels
are related to environmental exposures.
Blood Cotinine Concentrations in Children Aged 4-17
by Race and Ethnicity, 1988-1994 Versus 1999-2002
100 -
= 60
40
20
Total
Black,
non-Hispanic
63.7
23.7
41.0
16.5
57.9
36.6
59.4
22.4
Mexican
American
72.8
10.7
White,
non-Hispanic
41.3
5.2
24.2
35.5
19.1
1988-
1994
1999-
2002
1988- 1999-
1994 2002
1988-
1994
1999-
2002
1988- 1999-
1994 2002
Cotinine concentrations are reported for nonsmoking
children only.
Concentrations are measured in nanograms of cotinine
per milliliter of blood (ng/mL).
Source: Federal Interagency Forum on Child and Family Statistics, 2005
Concentration:
DO.05 to 1.0 ng/mL
D More than 1.0 ng/mL
Chapter 4 Human Exposure and Health 25
Exposure to Environmental Contaminants
-------
HEALTH STATUS
A nation's health status can be
measured in many ways. Life
expectancy and death rates are
generally regarded as good
overall measures of population health because they rep-
resent the combined effects of many different risk fac-
tors. Infant death rates are particularly useful because
they indicate the current health status of the population,
predict the health of the next generation, and reflect the
overall state of maternal health.
KEY POINTS
Overall, the health of the U.S. population has con-
tinued to improve. Mortality rates continue to decline,
and life expectancy continues to increase, due to factors
such as improved medical care over the past few
decades.
Life expectancies in the United States are lower,
however, than in many other countries. In 2004, the
United States ranked 35th in life expectancy for men
and women among the 192 nations and states that are
members of the World Health Organization.
The three leading causes of death in the United
States—heart disease, cancer, and stroke—remain
unchanged since 1999. Measures of premature death
show that injuries are the leading cause of death, fol-
lowed by cancer and heart disease.
Infant mortality in the United States shows a long-
term decline, although it remains among the high-
est in the industrialized world at nearly seven deaths
per every 1,000 live births in 2004. U.S. infant mortali-
ty rates were two to three times higher than the lowest
rates reported worldwide.
Although national health is generally improving,
racial, ethnic, and gender differences persist. The
mortality rate for black infants is still more than twice
that of white or Hispanic infants. The gap in life
expectancy between the black and white populations,
and male and female populations, is approximately
five years (see graphic). Though the largest decline in
overall mortality rates has been observed in black
males, overall mortality in this group continues to be
highest compared with white males and white and
black females. Currently, data available for other racial
or ethnic groups enable only limited analysis.
Tracking these kinds of broad health measures helps to
identify general patterns in the nation's health status and
lay a foundation for studying trends in specific diseases
and conditions. In addition, such tracking can help iden-
tify possible environmental factors that could contribute
to the diseases or conditions that are the leading causes
of death in the United States.
Life expectancy and death rates do not address
other aspects of health such as perceived well-
being or quality of life. Though life expectancy and
death rates are widely accepted measures of health
status, they alone do not completely describe the
nation's health.
Life Expectancy at Birth by Race and Sex,
1940-2004
Life expectancy is the average
number of years at birth a person
could expect to live if current
patterns in death rates were to
continue for the rest of that
person's life.
Source: National Center for Health Statistics, 2006,2007
Chapter 4 Human Exposure and Health 26
Health Status
-------
DISEASES AND HEALTH CONDITIONS
Exposure to environmental con-
taminants has been linked to
many human diseases and con-
ditions, including cancer, cardio-
vascular disease, respiratory disease, some infectious
diseases, and low birthweight. These links have been
established through well-designed studies with specified
populations and specific environmental exposures. Many
other risk factors can also lead to these diseases and con-
ditions, however. For all the diseases and conditions
KEY POINTS
described here, exposure to environmental contaminants
is just one of the possible risk factors.
Tracking the occurrence of these human diseases and
conditions at the national level helps identify general
patterns or trends over time and across subgroups.
Some notable differences are seen across different age
groups, races, or ethnic groups for many conditions,
such as heart and lung conditions, cancer, asthma, and
some birth outcomes, such as birth defects, pre-term
deliveries, and low birthweight.
As the U.S. population ages, many chronic dis-
eases—including various cancers and heart and lung
diseases—are occurring more frequently in adults.
For a number of these diseases, however, occurrence
has stabilized in recent years. The annual incidence
(proportion of new cases in a year) of cancer increased
slowly from the early 1970s to the early 1990s and then
leveled off. Rates for most of the major cardiovascular
and chronic obstructive pulmonary diseases remained
fairly constant between 1997 and 2006, though death
rates associated with these diseases declined.
There has been a slight overall rise in the incidence
of cancer in children ages 0 to 19 years since the
early 1970s. Leukemia and cancers of the brain and
nervous system remain the leading cancers in children.
Higher rates of cancer consistently occur among white
children compared to black children.
Asthma rates are higher in children and adolescents
than in adults, with some distinct patterns across
races (see graphic). Between 1980 and 1996, child-
hood asthma rates increased about 4 percent each
year, with no major shifts observed since 1997. Based
on data from 2006, approximately 10 million children
(about one in eight) in the United States were reported
as having been diagnosed with asthma. American
Indians/Alaska Natives and blacks experience the high-
est asthma rates compared to those reported in other
races. Rates are lower in Hispanic/Latino children v
and adults than in non-Hispanics/Latinos. N.
No notable patterns were observed for most
reportable infectious diseases between 1995 and
2005. However, some increases were reported between
2002 and 2005 in Lyme disease, Rocky Mountain spot-
ted fever, and Legionnaires' disease.
The proportion of mothers that gave birth early
(before 37 weeks of gestation) increased by 14
percent from 1990 to 2002, with a smaller increase
from 1995 to 2004. Data from 1995 to 2004 also
show that black mothers were about one-and-a-half
to two times more likely to give birth early than white
mothers. Also, black babies born at full term were
more likely to have a low birthweight (less than 2,500
grams, or 5 pounds 8 ounces) than white babies.
These indicators provide important insights on dis-
ease patterns but cannot be used alone to under-
stand the role of environmental contaminant
exposures. This is because these diseases and condi-
tions are linked to other causes besides environmental
exposures. Also, national indicators are not available for
other diseases with possible links to environmental con-
taminants, such as behavioral and neurodevelopmental
disorders, and other diseases still being studied for
possible connections to environmental contaminant
exposure, like Alzheimer's disease and diabetes.
Asthma Prevalence by Race, 2003-2005
200
160-
120-
40-
All groups
I White
I Black
American Indian/
Alaska Native
I Asian
Children
(0-17 years)
Adults
(18+years)
Asthma prevalence represents individuals who were ever told that they have
asthma.
Data were collected from 2003 to 2005.
Source: National Center for Health Statistics, 2007
Chapter 4 Human Exposure and Health 27
Diseases and Health Conditions
-------
COLOGICAL
CONDITION
Patterns in
Ecological Systems
Biological Diversity
Ecological Processes
Physical and
Chemical Attributes
of Ecological Systems
cological condition refers to the state of the
physical, chemical, and biological characteris-
tics of the environment and the processes and
interactions that connect them. Ecological condi-
tion reflects a wide array of factors, including the
natural development of plant and animal commu-
nities, natural disturbances, resource management,
pollution, and invasive species.
One approach to assessing the nation's ecological
condition is to examine its essential attributes,
including the extent, distribution, and diversity of
ecosystems; ecological processes; physical and
chemical attributes; and exposure to pollutants.
Human activities and natural factors can directly or
indirectly affect one or more of these attributes,
resulting in changes to an ecological system. For
example, plant growth might increase in response
to heavy rainfalls or decrease in response to con-
taminant exposure. Such changes can affect the
way an ecosystem functions and can have positive
or negative consequences for society—such as by
altering crop, timber, or fishery yields.
Measuring the nation's ecological condition is chal-
lenging. It is not as straightforward as measuring
pollutant levels in air, water, and soil. For example,
there are numerous groups of animals and plants,
but indicators are available for only some of these.
Major groups known to be undergoing changes,
such as amphibians, are not captured by the
available indicators.
Ecological Exposure
to Contaminants
Chapter 5: Ecological Condition
-------
PATTERNS IN ECOLOGICAL SYSTEMS
Ecological systems—ranging
from forests and watersheds to
wetlands and coral reefs—make
up the environment. Changes in
patterns of the extent and distribution of ecological sys-
tems have a fundamental influence on the health of the
planet and the people who depend on these systems.
For example, the extent of a forest affects both air and
water quality while the type of trees in a forest influ-
ences ecosystem structure and function, including which
animals and plants are present.
Ecological systems are not isolated, but connected to one
another. Connectivity refers to the way in which matter,
energy, and organisms flow within and among ecosystems.
Fragmentation refers to the breaking up of an ecological
system into smaller, more isolated parts. When ecological
systems become fragmented, habitat is broken up into
patches interspersed with other habitat types that might
not support the species that were originally present.
Patterns in ecological systems can change in response to
natural factors as well as human activities. Natural
changes can occur gradually as a result of geological and
climatic changes, or more quickly due to events such as
extreme weather or wildfires. Human activities that can
affect ecological systems include urbanization, agricul-
ture, forest management, introduction of invasive species,
and the release of greenhouse gases, which contributes
to climate change.
The impact of such changes varies depending on the geo-
graphic scale. For example, a storm could create a gap in a
forest canopy that only affects the immediate area for sev-
eral decades. In contrast, widespread loss of wetlands over
a large region could permanently shift bird migration
routes or make coastlines more vulnerable to hurricanes.
K.
EY POINTS
The total acreage of forest land nationwide
declined between the 1930s and the 1970s, but
increased over the last three decades. Trends in
forest acreage vary by region and by forest type. For
example, in the West, the acreage of fir-spruce and
hardwood forest increased over the past 50 years,
while the extent of other forest types, including
many pine forests, decreased (see graphic).
Slightly more than 26 percent of the forest land in
the lower 48 states occurs in landscapes completely
dominated by forest, while 19 percent of forest land
is considered highly frag-
mented. Forests can be
fragmented by human
activities and by natural
factors such as forest fires.
Little information is available on the extent of
ecological systems other than forests and wet-
lands, or about the effects of fragmentation on
biodiversity and ecological processes at different
geographic scales.
r
Timberland Area in the West by Forest Type, 1953-2002
Some ecological systems
remain highly connected
and intact. In the North-
east and Mid-Atlantic and
on the West Coast, rough-
ly 30 percent or more of
forest land remains unfrag-
mented. In the Southeast,
forests, wetlands, and
open water ecological
systems remain connected
to each other across 43
percent of the landscape.
£ 30
J 20
Douglas-fir
Ponderosa-Jeffrey
pine
Fir-spruce
Hemlock-Sitka
spruce
Lodgepole pine
Graphic depicts data for states in the western United States (including Alaska and
Hawaii), based on U.S. Department of Agriculture Forest Service reporting regions
(see map at right). Forest type is measured only on timberland, which is forest
that could potentially be used to produce commercial timber. Timberland covers
39 percent of the forested land in the West.
Source: U.S. Department of Agriculture Forest Service, 2001, 2004
Chapter 5 Ecological Condition
29
Patterns in Ecological Systems
-------
BIOLOGICAL DIVERSITY
Biological diversity, or biodiversi-
ty, refers to the amount of varia-
tion within biological systems.
This diversity occurs on multiple
levels—from the genetic makeup of a single organism to
the composition of an entire ecosystem. Biological diversi-
ty provides many tangible benefits to society, including
medicines and crops; for many people, it also contributes
in important ways to the quality of life.
Trends in the number and composition of species within
an ecological system are important indicators of the sys-
tem's health and robustness. Scientists generally agree
that as the number of species in an ecological system
declines, the system is less able to recover from stress.
These relationships are not straightforward and can vary
in degree, depending on the types of species intro-
duced or removed from a system.
Diversity arises over time when adaptation results in new
species that fill available niches in the environment. This is
a dynamic process involving colonization, evolution of
species adapted to new conditions, and extinction of
species that are less well adapted to a changing environ-
ment. This process has occurred over millions of years
across large geographic areas, punctuated occasionally
by significant natural events such as meteor strikes, peri-
ods of intense volcanic activity, and ice ages.
Human activities—such as urbanization, water manage-
ment, and land use changes—can have profound effects
on biological diversity, and in a much shorter timeframe.
For example, in sewage-polluted waters, dense beds of a
single species, sludgeworms, can replace
the more diverse communities of bot-
tom-dwelling organisms ordinarily
present. Invasive species also can
have widespread effects. As the
sea lamprey spread through
the Great Lakes in the mid-20th
century, for instance, sweeping
changes occurred throughout the
entire food web.
KEY POINTS
Watersheds covering almost one-quarter of the
area of the lower 48 states have lost at least one-
tenth of the native freshwater fish species known
to have been present at some time prior to 1970.
Losses are especially severe in the Southwest and the
Great Lakes, where eight watersheds have lost more
than half their native fish species. Fish diversity can
decline for a number of reasons, such as pollution,
habitat alteration, fisheries management, and inva-
sive species. In contrast, watersheds covering
about 21 percent of the lower 48 states have
retained all of their native species.
In recent years, changes (both decreases and
increases) have occurred in bird populations
in various habitats. Changes in bird populations
reflect changes in landscape and habitat, food avail-
ability and quality, toxic chemical exposure, and
climate. Since 1966, substantial decreases occurred
in 70 percent of grassland species and 36 percent of
shrubland species. Substantial increases occurred in
40 percent of urban species and 38 percent of water
and wetland species (see graphic).
For several aspects of biological diversity, there
are no consistent national indicators. These
include major groups of animals such as amphibians,
reptiles, and mammals; plants; and the numbers of
threatened, endangered, and invasive species.
Change in Bird Populations by Habitat Type, 1966-2003
200
175-
, 150-
[l25-
; 100-
l 75-
3
- 50-
25-
0
Population change:
• Substantial increase
D No substantial change
el Substantial decrease
in
—
Grassland Shrubland Woodland
Habitat type
Urban
Water/
wetland
Data gathered by the North American Breeding Bird Survey, which covers
the lower 48 states and southern Canada.
Substantial increases or decreases are those in which the observed
populations increased or decreased by more than two-thirds.
Source: Audubon Society, 2004
Chapter 5 Ecological Condition
30
Biological Diversity
-------
1*1
ECOLOGICAL PROCESSES
Ecological systems are sustained
by biological, physical, and
chemical processes. One such
process is carbon cycling.
During photosynthesis, plants use the sun's energy to
produce organic matter from carbon dioxide. This
organic matter provides the food at the base of the food
web. Carbon dioxide is regenerated through the respira-
tion of animals in the food web and through decomposi-
tion by the microbial community when organisms die.
Organisms that produce organic matter from inorganic
matter using energy from the sun are known as primary
producers. They range in size from microscopic ocean
plants to the giant redwoods of California. Decreases in
primary production affect all the animal populations that
KEY POINTS
depend on that production for food. Too much primary
production (for example, algal blooms in water bodies) is
also a problem.
Many human and natural factors impact ecological
processes, including pollution and changes in land use,
such as conversion of forests to urban or agricultural
land. Trends in ecological processes, such as the cycling
of carbon and carbon storage, provide insight into the
structure and function of ecological communities and
how human and natural factors affect them.
Although there are numerous components of the carbon
cycle, an indicator is available for only one of these com-
ponents—carbon storage in forests. This indicator pro-
vides insight into a portion of the carbon cycle for forest
ecosystems.
Overall, the net storage of carbon in U.S. forests
has been positive since 1953. The rate of storage
increased between the 1950s and 1980s, but declined
from 1987 to 1996. Net storage reflects the growth of
trees minus the amount of carbon lost through harvest
ing, land use change, or disturbances such as fire,
insects, and disease. The greatest amount of carbon is
being stored in the North, followed by the Rocky
Mountain region. Carbon storage has decreased in the
South, possibly due to an increase in harvesting com-
pared to growth (see graphic).
A number of gaps exist in understanding trends in
ecological processes. Currently, no reliable national
indicators are available for primary production, nutri-
ent retention and processing, or reproduction and
growth rates for plant and animal populations. There
are also no national indicators for other functions that
ecosystems perform, such as the provision of natural
resources and regulation of air and water quality. No
indicator is available for carbon stored in forest soil or
in other ecosystems.
Carbon Storage in Forests by Region, 1953-1996
Data gathered in the lower 48 states. Carbon storage is measured only on timberland,
which is forest that could potentially be used to produce commercial timber.
Timberland covers about two-thirds of the forested land of the lower 48 states.
Source: U.S. Department of Agriculture Forest Service, 2004
Chapter 5 Ecological Condition
31
Ecological Processes
-------
PHYSICAL AND CHEMICAL ATTRIBUTES OF ECOLOGICAL SYSTEMS
Physical attributes of ecological
systems include air temperature,
light, rainfall, and sea level.
Chemical attributes include dis-
solved oxygen, nutrient levels, acidity, and salinity. These
attributes shape evolution, drive ecological processes,
and govern the nature of ecological systems. Even small
changes in these attributes, such as changes in the acidi-
ty of a stream or the timing of rainfall in a desert, can
have potentially large effects on ecological systems.
As species evolve, they respond to and reflect the physical
and chemical attributes of the ecological systems in which
they live. For example, species that evolved in tropical
KEY POINTS
Since 1901, U.S. and global temperatures have
risen at an average rate of 0.12°F per decade (see
graphic). Lately, the rate of warming has increased.
Over the last 30 years, temperatures rose by 0.59°F per
decade in the lower 48 states and 0.31 °F per decade
worldwide (see graphic). These trends are consistent
with reduced snow cover, earlier spring ice melt, and
increased sea surface temperature, all of which can
affect ecological systems. It is very likely that most of
the observed temperature increase is due to ris-
ing levels of greenhouse gases in the atmos- *x^
phere caused by human activities. ^
Sea levels rose steadily at many coastal locations
between 1950 and 1999, particularly the Mid-
Atlantic coast (3 to 6 millimeters per year) and at
two sites in Louisiana (as high as 9 to 12 millime-
ters per year). These rates are based on tidal gauges
that measure relative sea level rise, which accounts for
sea and land height changes but does not distinguish
between the two. Sea level rise can alter ecological
conditions in coastal areas. Effects can include
increased flooding and loss of freshwater systems as
they are transformed into inland salt waters or open
coastal waters.
About 25 percent of the nation's small streams
show strong evidence of excess fine sediments,
which can diminish habitat for aquatic life. Various
land use practices, as well as modifications in stream
flows, can lead to excess sedimentation in streams.
Gaps remain in assessing national trends in the
physical and chemical attributes of ecological sys-
tems. Recent monitoring programs have provided a
baseline for national trends in nutrients, acidity, and
other factors in streams and estuaries. However, there
waters require higher, less variable temperatures than
species that evolved in temperate waters, where average
temperatures are lower and fluctuate more. Similarly, peri-
odic floods or fires are essential to sustain many species in
areas where such events have occurred over thousands or
millions of years.
Many factors can alter the physical and chemical character-
istics of ecological systems. For example, acid rain can
increase the acidity of lakes in some regions. Damming or
channelizing rivers can alter the flooding and sedimentation
processes that sustain particular types of systems, such as
wetlands. Changes in climate can alter species diversity and
nearly every aspect of ecological structure and function.
still is a lack of trend data or historical baselines for
some attributes, such as water levels in lakes, amount of
snowpack, and long-term patterns of flooding and fires.
U.S. and Global Mean Temperatures, 1901-2006
U.S. temperature anomalies
Global temperature anomalies
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
U.S. data gathered in the lower 48 states.
"Anomaly" is the difference between the observed temperature and a
standard that was chosen for comparison. In this case, the standard
is the average temperature over the period 1961-1990.
Source: National Oceanic and Atmospheric Administration, 2007
Chapter 5 Ecological Condition
32 Physical and Chemical Attributes of Ecological Systems
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ECOLOGICAL EXPOSURE TO CONTAMINANTS
Plants and animals can be
exposed to chemicals in the
environment through air, water,
soil, and food. If concentrations
of these chemicals are too great, the reproduction,
health, or survival of the individual plant or animal—or
organisms that consume it—can be threatened. If
enough individuals in a species (or more than one
species) are affected, changes in the ecosystem structure
and function can result.
Once inside an organism, certain chemicals build up over
time with repeated exposure. This process is called bioac-
cumulation. Exposure to these chemicals can be deter-
mined by measuring chemical concentrations in plant and
animal tissues. Other chemicals do not bioaccumulate but
can still cause harm. For example,
ozone pollution can damage
the leaves of plants. Direct * 9
observations can indicate
exposure to contaminants
if the damage is visible.
\
KEY POINTS
In many areas of the country, at least 20 per-
cent of ozone-sensitive forest plants show at
least some injury from ozone pollution (see
graphic). The Mid-Atlantic and Southeast show the
highest levels of injury, while the Rocky Mountains
and Pacific Northwest show no damage. Ozone
pollution in the lower atmosphere can affect
forest ecosystems. Damage to leaves is usually
the first visible sign of injury to plants from ozone
exposure.
Tissues from both coastal and freshwater
fish contain bioaccumulative chemicals, such
as the pesticide DDT or dichloro-diphenyl-
trichloroethane, mercury, and polychlorinated
biphenyls (PCBs). While exposure to these chemi-
cals is occurring at variable levels throughout the
country, scientists have not fully assessed the eco-
logical effects of these exposures. These chemicals
are known to affect coastal and freshwater fish
species, but there are currently no national thresh-
old levels for harmful effects to fish.
No consistent national indicators are available
that measure the level of chemicals in plants or
in wildlife other than fish. Therefore, no national
trends are available for exposure of plants and ani-
mals to many common environmental pollutants.
Ozone Injury to Forest Plants by EPA Region, 2002
Region! Region 2 Regions
Region 7
Region 8
Region 9
Region 10
Data gathered from 945 monitoring sites
in 41 states. Graphic shows the percent
of monitoring sites in each category.
Source: U.S. Department of Agriculture
Forest Service, 2006
Chapter 5 Ecological Condition
Ecological Exposure to Contaminants
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LOOKING AHEAD
Written for a general audience, EPA's 2008 Report on the Environment: Highlights
of National Trends summarizes some of the more important findings from a
more comprehensive companion report, EPA's 2008 Report on the Environment.
The topics presented in this document provide important insight into what
scientists know—and do not know—about current conditions and trends for the
nation's air, water, land, human health, and ecological systems.
This information is based on environmental indicators and is presented at a
national or regional level. Many other sources on the environment are available,
including some that address issues at a more local level:
• EPA's Web site, www.epa.gov, is a good starting place to get more information
on a particular topic or on a specific city or region of the country.
• Links to individual state environmental departments are available at:
www.epa.gov/epahome/state.htm.
• Links to some actions that individuals can take to protect the environment
and their own health are available at: www.epa.gov/roe.
EPA is just one of many organizations working to fill the gaps in our under-
standing of the environment. As those gaps are filled, a more complete
picture of the nation's environment will emerge.
EPA plans to report periodically on the state of the environment through
publications like this one. In addition, the electronic version of the report
(www.epa.gov/roe) will present new data as they become available and
allow users to offer suggestions for making this report more useful. Your
input is welcome.
ABOUT THE INDICATO
The content of Highlights of National Trends is derived from EPA's 2008 Report
on the Environment, which features detailed information on 85 environmental
indicators. Most of these indicators are national in scope; however, regional
indicators have been used in some cases to illustrate important scenarios and
could be applied to the nation in the future. A subset of these indicators is
presented in this document.
EPA selected indicators to highlight in this document based on their complete-
ness, importance to the public and the scientific community, ability to show a
meaningful trend, and ability to address a key environmental question.
Indicators developed since EPA's Draft Report on the Environment 2003 were
also given priority.
ENVIRONMENTAL INDICATORS
The indicators used in the Report on the Environment:
• Rely on actual measurements of environmental and
human health conditions over time.
• Meet a set of standards, which include quality, accura-
cy, relevance, and comparability.
• Were reviewed by an independent scientific panel to
ensure that they meet these standards.
Are national (or in some cases regional) in coverage.
They do not describe trends or conditions for a specific
locale.
Come from many governmental and non-governmental
organizations, which collect data at different time peri-
ods and for varying purposes.
Can only partially answer the key questions.
Looking Ahead
34
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LIST OF INDICATORS
Indicators included in EPA's 2008 Report on the Environment are listed below, along with the key environmental question each indicator
attempts to answer. Indicators with an asterisk* are featured in Highlights of National Trends.
AIR
OUTDOOR AIR
What are the trends in outdoor
air quality and their effects on
human health and the
environment?
• Carbon Monoxide Emissions*
• Ambient Concentrations of
Carbon Monoxide*
• Lead Emissions*
• Ambient Concentrations of Lead*
• Nitrogen Oxides Emissions*
• Ambient Concentrations of
Nitrogen Dioxide*
• Volatile Organic Compounds
Emissions*
• Ambient Concentrations of
Ozone*
• Ozone Injury to Forest Plants
• Particulate Matter Emissions*
• Ambient Concentrations of
Particulate Matter*
• Sulfur Dioxide Emissions*
• Percent of Days With Air Quality
Index Values Greater Than 100
• Mercury Emissions*
• Air Toxics Emissions*
• Ambient Concentrations of
Benzene*
• Ozone and Particulate Matter
Concentrations for U.S. Counties
in the U.S./Mexico Border
Region
• Ambient Concentrations of
Manganese Compounds in EPA
Region 5
ACID RAIN AND REGIONAL HAZE
What are the trends in outdoor
air quality and their effects on
human health and the
environment?
• Nitrogen Oxides Emissions*
• Regional Haze*
• Sulfur Dioxide Emissions*
• Acid Deposition*
• Lake and Stream Acidity*
• Particulate Matter Emissions
OZONE DEPLETION
What are the trends in outdoor
air quality and their effects on
human health and the
environment?
• Concentrations of Ozone-
Depleting Substances*
• Ozone Levels Over North
America*
GREENHOUSE GASES
What are the trends in green-
house gas emissions and
concentrations?
• U.S. Greenhouse Gas Emissions*
• Atmospheric Concentrations of
Greenhouse Gases*
INDOOR AIR
What are the trends in indoor
air quality and their effects on
human health?
• U.S. Homes Above EPA's Radon
Action Level*
• Blood Cotinine Level*
WATER
FRESH SURFACE WATERS
What are the trends in the extent
and condition of fresh surface
waters and their effects on human
health and the environment?
• High and Low Stream Flows*
• Streambed Stability in
Wadeable Streams
• Lake and Stream Acidity*
• Nitrogen and Phosphorus in
Wadeable Streams*
• Nitrogen and Phosphorus in
Streams in Agricultural
Watersheds
• Nitrogen and Phosphorus Loads
in Large Rivers*
• Pesticides in Streams in
Agricultural Watersheds
• Benthic Macroinvertebrates in
Wadeable Streams*
GROUND WATER
What are the trends in the
extent and condition of ground
water and their effects on
human health and the
environment?
• Nitrate and Pesticides in Shallow
Ground Water in Agricultural
Watersheds*
WETLANDS
What are the trends in the
extent and condition of wet-
lands and their effects on
human health and the
environment?
• Wetland Extent, Change, and
Sources of Change*
COASTAL WATERS
What are the trends in the
extent and condition of coastal
waters and their effects on
human health and the
environment?
• Wetland Extent, Change, and
Sources of Change
• Trophic State of Coastal Waters*
• Coastal Sediment Quality
• Coastal Benthic Communities*
• Coastal Fish Tissue Contaminants
• Submerged Aquatic Vegetation
in the Chesapeake Bay*
• Hypoxia in the Gulf of Mexico
and Long Island Sound*
DRINKING WATER
What are the trends in the
quality of drinking water and
their effects on human health?
• Population Served by
Community Water Systems
With No Reported Violations of
Health-Based Standards*
RECREATIONAL WATERS
What are the trends in the con-
dition of recreational waters
and their effects on human
health and the environment?
There are currently no national
indicators available for this topic.
CONSUMABLE FISH AND
SHELLFISH
What are the trends in the con-
dition of consumable fish and
shellfish and their effects on
human health?
• Coastal Fish Tissue
Contaminants*
• Contaminants in Lake Fish
Tissue*
LAND
LAND COVER
What are the trends in land cover
and their effects on human
health and the environment?
• Land Cover*
• Forest Extent and Type*
• Land Cover in the Puget
Sound/Georgia Basin
LAND USE
What are the trends in land use
and their effects on human
health and the environment?
• Land Use*
• Urbanization and Population
Change*
List of Indicators
35
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WASTES AND THE
ENVIRONMENT
What are the trends in wastes
and their effects on human
health and the environment?
• Quantity of Municipal Solid
Waste Generated and Managed*
• Quantity of RCRA Hazardous
Waste Generated and Managed*
CHEMICALS APPLIED AND
RELEASED TO LAND
What are the trends in chemi-
cals used on the land and their
effects on human health and
the environment?
• Fertilizer Applied for Agricultural
Purposes*
• Toxic Chemicals in Production-
Related Wastes Combusted for
Energy Recovery, Released,
Treated, or Recycled*
• Pesticide Residues in Food*
• Reported Pesticide Incidents
CONTAMINATED LANDS
What are the trends in contam-
inated lands and their effects
on human health and the
environment?
• Current Human Exposures
Under Control at High-Priority
Cleanup Sites*
• Migration of Contaminated
Ground Water Under Control at
High-Priority Cleanup Sites*
HUMAN EXPOSURE
AND HEALTH
EXPOSURE TO ENVIRONMENTAL
CONTAMINANTS
What are the trends in human
exposure to environmental
contaminants including across
population subgroups and
geographic regions?
• Blood Lead Level*
• Blood Mercury Level*
• Blood Cadmium Level
• Blood Cotinine Level*
• Blood Persistent Organic
Pollutants Level*
• Urinary Pesticide Level*
• Urinary Phthlate Level*
HEALTH STATUS
What are the trends in health
status in the United States?
• General Mortality*
• Life Expectancy at Birth*
• Infant Mortality*
DISEASES AND HEALTH
CONDITIONS
What are the trends in human
disease and conditions for
which environmental pollutants
may be a risk factor, including
across population subgroups
and geographic regions?
• Cancer Incidence*
• Childhood Cancer Incidence*
• Cardiovascular Disease
Prevalence and Mortality*
• Chronic Obstructive Pulmonary
Disease Prevalence and Mortality*
• Asthma Prevalence*
• Infectious Diseases Associated
With Environmental Exposures or
Conditions*
• Birth Defects Prevalence and
Mortality
• Low Birthweight*
• Preterm Delivery*
ECOLOGICAL
CONDITION
PATTERNS IN ECOLOGICAL
SYSTEMS
What are the trends in the
extent and distribution of the
nation's ecological systems?
• Land Cover
• Forest Extent and Type*
• Forest Fragmentation*
• Wetland Extent, Change, and
Sources of Change
• Land Use
• Urbanization and Population
Change
• Land Cover in the Puget
Sound/Georgia Basin
• Ecological Connectivity in EPA
Region 4*
• Relative Ecological Condition
of Undeveloped Land in EPA
Region 5
BIOLOGICAL DIVERSITY
What are the trends in the diver-
sity and biological balance of the
nation's ecological systems?
• Coastal Benthic Communities
• Benthic Macroinvertebrates in
Wadeable Streams
• Bird Populations*
• Fish Faunal Intactness*
• Submerged Aquatic Vegetation
in the Chesapeake Bay
• Non-Indigenous Species in the
Estuaries of the Pacific Northwest
ECOLOGICAL PROCESSES
What are the trends in the eco-
logical processes that sustain
the nation's ecological systems?
• Carbon Storage in Forests*
PHYSICAL AND CHEMICAL
ATTRIBUTES OF ECOLOGICAL
SYSTEMS
What are the trends in the criti-
cal physical and chemical
attributes and processes of the
nation's ecological systems?
• U.S. and Global Mean
Temperature and Precipitation*
• Sea Surface Temperature
• High and Low Stream Flows
• Streambed Stability in
Wadeable Streams*
• Sea Level*
• Nitrogen and Phosphorus Loads
in Large Rivers
• Nitrogen and Phosphorus in
Streams in Agricultural
Watersheds
• Nitrogen and Phosphorus in
Wadeable Streams
• Lake and Stream Acidity
• Hypoxia in the Gulf of Mexico
and Long Island Sound
ECOLOGICAL EXPOSURE TO
CONTAMINANTS
What are the trends in biomea-
sures of exposure to common
environmental pollutants in
plants and animals?
• Coastal Fish Tissue
Contaminants*
• Ozone Injury to Forest Plants*
• Contaminants in Lake Fish
Tissue*
List of Indicators
36
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AC KNOWLEDG EM ENTS
HIGHLIGHTS DOCUMENT
Ethan McMahon (EPA)
Project Lead
Suzanne Annand (EPA)
Gerry Bakker (EPA)
Gail Bentkover (EPA)
Vipul Bhatt (EPA)
Paul Borst (EPA)
Ethel Brandt (EPA)
Gerard Bulanowski (EPA)
Deborah Burgin (EPA)
Lael Butler (EPA)
Robert Cassell (EPA)
Heather Case (EPA)
Arden Calvert (EPA)
TEAM
Andrea Cherepy (EPA)
Julie Damon (EPA)
Nicoletta DiForte (EPA)
Sandra Duque (EPA)
Rick Durbrow (EPA)
Vance Fong (EPA)
Tom Forbes (EPA)
Debra Forman (EPA)
Michael Hadrick (EPA)
Belinda Hawkins (EPA)
Michelle Hiller-Purvis (EPA)
Matt Hoagland (EPA)
Elizabeth Jackson (EPA)
Marjorie Jones (EPA)
Monica Jones (EPA)
Stuart Kerzner (EPA)
Carrie Knowlton (EPA)
Danelle Lobdell (EPA)
Macara Lousberg (EPA)
Maricruz MaGowan (EPA)
Lawrence Martin (EPA)
Carmen Maso (EPA)
Jeff Maurer (EPA)
Ronald McHugh (EPA)
Jay Messer (EPA)
Patricia Murphy (EPA)
Laura Neilsen (EPA)
William Nickerson (EPA)
Nicole Paquette (EPA)
Randolph Perfetti (EPA)
William Rhea (EPA)
Denice Shaw (EPA)
Madalene Stevens (EPA)
Richard Sumpter (EPA)
Guy Tomassoni (EPA)
Winona Victery (EPA)
Beth Walls (EPA)
Nancy Wentworth (EPA)
Sherri White (EPA)
Ann Williamson (EPA)
NATIONAL ADVISORY COUNCIL FOR ENVIRONMENTAL POLICY AND TECHNOLOGY ROE WORKGROUP
Arleen O'Donnell
Massachusetts DEP
Co-chair
Don Watts
New Jersey Institute of
Technology
Co-chair
Jeff Crane
Colorado Watershed Assembly
Carolyn Green
Sunoco
John Howard
Vinson & Elkins
NACEPT Chair
George Lambert
University of Medicine and
Dentistry of New Jersey
SAB member
Stan Laskowski
University of Pennsylvania
Robert Olson
Institute for Alternative Futures
Bradley Smith
Western Washington University
Victoria Tschinkel
1000 Friends of Florida
Robert Twiss
University of California-Berkeley
SAB member
Sonia Altieri
EPA
Designated Federal Officer for
NACEPT
Thomas Armitage
EPA
Designated Federal Officer for
SAB
Acknowledgements
37
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United States
Environmental Protection
Agency
Office of Research and Development
National Center for Environmental Assessment
Washington, DC 20460
Official Business
Penalty for Private Use
$300
EPA-260-R-08-002
June 2008
www.epa.gov
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