National Water Quality Inventory:
Report to Congress
2004 Reporting Cycle
January 2009
United States Environmental Protection Agency
Office of Water
Washington, DC 20460
EPA 841-R-08-001
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National Water Quality Inventory: 2004 Report to Congress
Table of Contents
Section Page
List of Figures iv
List of Tables iv
List of Acronyms v
Executive Summary 1
I. Background 5
About the Water Quality Assessment and TMDL Information Database (ATTAINS) 5
Assessing Water Quality 7
II. Findings 13
Rivers and Streams 13
Lakes, Ponds, and Reservoirs 16
Bays and Estuaries 20
Other Waters 23
Coastal Resources 23
Great Lakes 24
Wetlands 24
III. Probability Surveys of Water Quality 26
National Coastal Assessment 26
The Wadeable Streams Assessment 27
Survey of the Nation's Lakes 29
National Rivers and Streams Assessment 30
National Wetland Condition Assessment 30
State-Scale Statistical Surveys 31
South Carolina 32
Indiana 33
Florida 34
IV. Future Reporting 36
V. References 37
in
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National Water Quality Inventory: 2004 Report to Congress
List of Figures
Figure Page
1 Water quality in assessed river and stream miles 13
2 Top 10 causes of impairment in assessed rivers and streams 15
3 Top 10 sources of impairment in assessed rivers and streams 16
4 Water quality in assessed lake acres 17
5 Top 10 causes of impairment in assessed lakes, ponds, and reservoirs 18
6 Top 10 sources of impairment in assessed lakes, ponds, and reservoirs 19
7 Water quality in assessed bay and estuary square miles 20
8 Top 10 causes of impairment in assessed bays and estuaries 22
9 Top 10 sources of impairment in assessed bays and estuaries 23
10 Findings of the National Coastal Condition Report III 27
11 Biological quality of the nation's streams 28
12 Extent of streams rated poor for aquatic stressors, and increase in risk of poor biology in
streams rated poor over streams rated good for each stressor 28
13 Sampling locations for the survey of the nation's lakes 29
14 Sampling locations for the national rivers and streams assessment 30
15 Summary of statewide condition for Florida rivers and streams (left) and large lakes (right)
(source: Integrated Water Quality Assessment for Florida: 2004 (FL DEP) 34
List of Tables
Table Page
1 Major Impairment Cause Categories Used in this Report 9
2 Major Pollutant Source Categories Used in this Report 10
3 Individual Use Support in Assessed River and Stream Miles 14
4 Individual Use Support in Assessed Lake, Reservoir, and Pond Acres 17
5 Individual Use Support in Assessed Bay and Estuary Square Miles 21
6 Traditional vs. Probability-based Assessment Results for Rivers and Streams in South
Carolina 33
7 Traditional vs. Probability-based Assessment Results for Estuaries in South Carolina 33
IV
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National Water Quality Inventory: 2004 Report to Congress
List of Acronyms
ATTAINS Assessment TMDL Tracking And ImplementatioN System (Water Quality
Assessment and TMDL Information)
BEACH Act Beaches Environmental Assessment and Coastal Health Act of 2000
DIN dissolved inorganic nitrogen
DIP dissolved inorganic phosphorus
EPA U.S. Environmental Protection Agency
FWS U.S. Fish and Wildlife Service
IBI Index of Biotic Integrity
NOAA National Oceanic and Atmospheric Administration
NFS National Park Service
PAHs polycyclic aromatic hydrocarbons
PCBs polychlorinated biphenyls
TMDL total maximum daily load
USGS U.S. Geological Survey
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VI
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National Water Quality Inventory: 2004 Report to Congress
Executive Summary
This National Water Quality Inventory: 2004 Report to Congress, prepared under section
305(b) of the Clean Water Act, summarizes water quality reports submitted electronically by 44
states, 2 territories, and the District of Columbia to the U.S. Environmental Protection Agency
(EPA) for the 2004 reporting cycle. These state water quality assessment findings are contained
in EPA's Water Quality Assessment
and Total Maximum Daily Load
(TMDL) Information database and
website, known as ATTAINS
(Assessment TMDL Tracking And
ImplementatioN System), for the
2004 reporting cycle. The ATTAINS
database is available online at the
website http://www.epa.gov/waters/ir.
EPA developed the Assessment TMDL Tracking And
ImplementatioN System (ATTAINS) database and website
to combine two formerly separate sites — the National
Assessment Database (for 305(b) water quality
assessment information) and the National Total Maximum
Daily Loads (TMDL) Tracking System (for 303(d) impaired
waters information). The ATTAINS database/website
includes state-re ported assessment decisions on the
support of designated uses (such as recreation) in
assessed waters; the waters that are impaired; the causes
of impairment (such as pathogens); the sources of
impairment (such as agriculture); and the status of actions
(TMDLs) to help restore impaired waters.
ATTAINS contains this information for each waterbody
assessed by the states and summarizes key waterbody
information by state, by region, and nationally. If a state
did not provide waterbody-specific information
electronically to EPA by the reporting deadline, it was not
included in this report. EPA worked extensively with the
states to assist in data submittal.
Summary findings of the 2004
state water quality reports are
presented below. It is important to
note that this information is for a
relatively small subset of the nation's
total waters which may not be
representative of the waters that were
not assessed. Because many states
target their limited monitoring
resources to waters that they suspect are impaired, there may be a lower percentage of impaired
waters among the non-assessed (and total) waters than among the assessed waters. Information
about specific sources and causes of impairment is incomplete because the states do not always
report the cause or source of pollution affecting every impaired waterbody. In some cases, states
may recognize that water quality does not fully support a designated use; however, they may not
have adequate data to document the specific pollutant or source responsible for the impairment.
EPA also made changes in how specific causes and sources are categorized for 2004, and these
changes in some cases affect how the findings of causes and sources of impairment compare to
findings of previous years. Readers are urged to consult the ATTAINS website for detailed
listings of the causes and sources of impairment reported by states.
Rivers and Streams
This report includes states' assessments of 16% of the nation's 3.5 million miles of rivers
and streams for the 2004 reporting cycle. Of these waterbodies, 44% were reported as impaired
or not clean enough to support their designated uses, such as fishing and swimming. States found
the remaining 56% to be fully supporting all assessed uses. Pathogens, habitat alterations, and
organic enrichment/oxygen depletion were cited as the leading causes of impairment in rivers
and streams, and top sources of impairment included agricultural activities, hydrologic
modifications (such as water diversions and channelization), and unknown/unspecified sources.
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National Water Quality Inventory: 2004 Report to Congress
Lakes and Reservoirs
This report includes states' assessments of 39% of the nation's 41.7 million acres of
lakes, ponds, and reservoirs during the 2004 reporting cycle. Of these waterbodies, 64% were
reported as impaired and 36% were fully supporting all assessed uses. Mercury, polychlorinated
biphenyls (PCBs), and nutrients were cited as the leading causes of impairment in lakes. Top
sources of pollutants to lakes, ponds, and reservoirs included atmospheric deposition,
unknown/unspecified sources, and agriculture.
Bays and Estuaries
This report includes states' assessments of 29% of the nation's 87,791 square miles of
bays and estuaries for the 2004 reporting cycle. Of these assessed waterbodies, 30% were
reported as impaired, and the remaining 70% fully supported all assessed uses. Pathogens,
organic enrichment/oxygen depletion, and mercury were reported as the leading causes of
impairment in bays and estuaries. Top sources of impairment to bays and estuaries included
atmospheric deposition, unknown/unspecified sources, and municipal discharges/sewage.
Probability Studies of Water Quality
EPA and states have embarked on a series of probability-based surveys that are discussed
later in this report. Probability-based surveys complement more traditional targeted monitoring
and assessment programs and add substantially to our understanding of state, regional, and
national water quality conditions. These studies select sites at random to provide estimates of the
condition of a population of waters throughout a state, region, or the nation. They describe the
percent of waters in a state or region supporting Clean Water Act goals and the percent of waters
affected by the stressors that are included in the study design, which can inform protection and
restoration priorities. Probabilistic surveys are a cost-effective approach for tracking changes in
condition and stressors across the population of waters of the United States. As more states
adopt probabilistic monitoring, EPA will be able to more accurately report on water quality
trends. This effort will also help inform water quality policy and ensure resources are
appropriately targeted. As of 2008, 30 states were participating in probabilistic water quality
surveys, and EPA has set a goal of having participation by all 50 states by 2011. To date, EPA
has provided $65 million in additional section 106 grant monitoring funds to help states improve
water quality monitoring programs and implement probabilistic survey designs.
Future Reporting
States are working to strengthen their water monitoring and assessment programs by
developing long-term monitoring strategies that identify the specific actions needed to move
toward more comprehensive and consistent reporting of water quality conditions. These actions
include implementing probability-based surveys in combination with more traditional monitoring
targeted to waters of interest. In addition, states and EPA have streamlined water quality
assessment and reporting by integrating various Clean Water Act reporting requirements and
facilitating and improving electronic reporting of water data. The results of these efforts will be
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National Water Quality Inventory: 2004 Report to Congress
more comprehensive and valid information that can be easily accessed by water quality
managers and the public in a timely fashion and used to describe water quality on a state,
regional, or national scale.
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National Water Quality Inventory: 2004 Report to Congress
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National Water Quality Inventory: 2004 Report to Congress
I. Background
Under section 305(b)(l)(A) of the Clean Water Act, states, territories, and other
jurisdictions of the United States are required to submit reports on the quality of their waters to
the U.S. Environmental Protection Agency (EPA) every 2 years. Historically, states submitted
these reports in hardcopy format, and EPA prepared a national hardcopy report that summarized
their findings (see http://www.epa.gov/305b/). Under section 303(d) of the Clean Water Act,
states also biennially provide a separate prioritized list of those waters that are impaired and
require the development of pollution controls (to learn more about section 303(d) reporting, visit
http://www.epa.gov/owow/tmdl/).
Beginning with the 2002 reporting cycle, EPA urged states to combine sections 305(b)
and 303(d) reporting requirements into one integrated report and to submit these reports
electronically. EPA has encouraged states to combine these reports for several reasons.
Integrating these reports merges environmental data from a variety of water quality programs,
increases the consistency of this information, benefits the public by providing a more informed
summary of the quality of assessed state waters, and provides decision makers with better
information on the actions necessary to protect and restore these waterbodies. The integrated
report also streamlines state reporting burdens by eliminating the need for two separate reports.
For the 2004 reporting cycle, 16 of the 44 water quality reports submitted by the states
were fully integrated. Progress toward full integration is expected in coming years. Data for both
integrated and non-integrated state reports are available on EPA's new Water Quality
Assessment and Total Maximum Daily Load (TMDL) Information database and website, known
as ATTAINS (Assessment TMDL Tracking and ImplementatioN System). To facilitate the
states' efforts to improve integrated reporting, EPA published reporting guidance in 2005 and a
series of clarifying memoranda in subsequent years. For more information on integrated
reporting, visit http://www.epa.gov/owow/tmdl/guidance.html#tmdl.
About the Water Quality Assessment and TMDL Information Database
(ATTAINS)
The Water Quality Assessment and TMDL Information database, known as ATTAINS
(for Assessment TMDL Tracking and ImplementatioN System), presents electronic water
quality information submitted since 2002 by the states, territories, and the District of Columbia.
ATTAINS allows the user to view, via the Internet, dynamic tables and charts that summarize
state-reported data for the nation as a whole, for individual states, for individual waters, and for
the ten EPA regions. It shows which waters have been assessed, which are impaired, and which
have plans (e.g., TMDLs) completed to help restore them. By displaying data in one location,
ATTAINS allows for a more informed summary of the quality of state waters that have been
assessed and provides decision makers with better information on the actions necessary to
protect and restore assessed waters of the U.S.
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National Water Quality Inventory: 2004 Report to Congress
To view ATTAINS, go to http://www.epa.gov/waters/ir and click on the map to find
summary information and assessment results for specific states, EPA regions, watersheds, and
waterbodies of interest. You can select information for a specific biennial reporting cycle (e.g.,
2002, 2004, etc) or the most recent available information across multiple cycles. A series of
tables and charts also summarize the status of assessed waters across the nation.
For this report, EPA has included ATTAINS data from 44 states, the District of
Columbia, the U.S. Virgin Islands and Puerto Rico. Pennsylvania, Maryland, Florida, Oregon,
Idaho, Hawaii, the tribal nations, and the island territories of the Pacific did not provide data
electronically that could be used for the 2004 reporting cycle. Although Pennsylvania, Florida,
and Oregon did publish hard copy section 305(b) water quality reports, EPA relies on the
electronic submittal by states of assessment information as the source of the water quality
findings in this report. Maryland and Hawaii submitted only impaired waters lists under section
303(d) in 2004 and did not provide information on assessed waters that were not impaired.
Idaho is submitting a combined 2004/2006/2008 integrated report in 2008. Although only 2004
reporting cycle data were used for this report, it is important to note that the ATTAINS database
contains all available waterbody-specific data reported by the states and territories from 2002 on.
About half the states conduct their own probability-based surveys (based on statistical
random sampling design) to complement this information and to draw state-wide conclusions
about the state's water resources. EPA fully supports these state efforts to provide more complete
assessments of their waters and to increase their percentage of assessed waters. Because state-
level probabilistic monitoring efforts are in their initial stages in many states, the results of these
state-scale probability surveys for the most part are not included in the 2004 ATTAINS database.
We expect that the 2008 version of the database will begin to do so, and that we will be able to
move toward water quality reports that assess all the states' waters, providing a valuable
complement to current knowledge on the subset of waters with targeted monitoring.
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National Water Quality Inventory: 2004 Report to Congress
Comparability of Water Quality Data
Although the information in ATTAINS provides a picture of state assessment results, these data should
not be used to compare water quality conditions between states, identify trends in statewide or national
water quality, or compare the impacts of specific causes or sources of impairment over time. The
following are reasons for this lack of comparability:
• The methods states use to monitor and assess their waters, including what and how they monitor
and how they report their findings to EPA, vary from state to state and within individual states
over time. Many states target their limited monitoring resources to waters they suspect are
impaired, or to address local priorities and concerns; therefore, the small percentage of waters
assessed may not reflect statewide conditions. States may monitor a different set of waters from
one reporting cycle to another, or may monitor fewer waters when state budgets are limited. It is
also important to note that six states did not provide electronic data for the 2004 reporting cycle,
and that the lack of data from these states affects the summary statistics.
• The science of monitoring and assessment varies over time, and many states are better able to
identify problems as their monitoring and analytical methods improve. For example, states are
conducting more fish tissue sampling than in previous years. The use of improved assessment
methods to collect better information may result in more extensive and protective fish
consumption advisories, even though water quality conditions themselves may not have changed.
• For the 2004 reporting cycle, EPA re-evaluated how it grouped sources and causes reported by
the states into larger overall categories (such as municipal discharges/sewage or metals other
than mercury) for national reporting purposes. The purpose of this re-evaluation was to more
accurately categorize the source and cause information reported by the states. Some overall
source and cause categories were renamed, and some state-re ported sub-categories were
moved into different overall categories compared to the 2002 reporting cycle. (See the section
Sources of Impairment in this report for more information.)
• Under the Clean Water Act, each state has the authority to set its own water quality standards;
therefore, a state's definition of its designated uses (for example, Warm Water Fishery or
Livestock Watering) may differ from definitions used by other states, along with the criteria
against which states determine impairments. (See the section Assessing Water Quality, below,
for more information.)
Assessing Water Quality
States assess the quality of their waters based on water quality standards they develop in
accordance with the Clean Water Act. Water quality standards may differ from state to state, but
must meet minimum requirements. EPA must approve these standards before they become
effective under the Clean Water Act.
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National Water Quality Inventory: 2004 Report to Congress
Designated Use Categories in this Report
The states have different names for the various uses they have designated for their waters. For
example, one state might designate as Class A those waters that are capable of supporting fish
species of commercial and recreational value (e.g., salmon, trout), whereas another state might
classify similar waters as Cold Water Fishery waters. The ATTAINS database groups state-re ported
uses according to the following overall categories:
• Fish, Shellfish, and Wildlife Protection and Propagation - Is water quality good enough to
support a healthy, balanced community of aquatic organisms?
• Recreation - Can people safely swim or enjoy other recreational activities in and on the water?
• Public Water Supply - Does the waterbody safely supply water for drinking after standard
treatment?
• Aquatic Life Harvesting - Can people safely eat fish caught in the waterbody?
• Agricultural - Can the waterbody be used for irrigating fields and watering livestock?
• Industrial - Can the water be used for industrial processes?
• Aesthetic Value - Is the waterbody aesthetically appealing?
• Exceptional Recreational or Ecological Significance - Does the waterbody qualify as an
outstanding natural resource or support rare or endangered species?
You can find out which state classifications fit under each of these categories by clicking on the
individual use category name in the ATTAINS database.
Water quality standards consist of three elements: the designated uses assigned to waters
(e.g., recreation, public water supply, the protection and propagation of aquatic life); the criteria
or thresholds (expressed as numeric pollutant concentrations or narrative requirements) that are
necessary to protect the designated uses; and the anti-degradation policy intended to prevent
waters from deteriorating from their current condition. Waters may be designated for more than
one use. To learn more about water quality standards, visit
http: //www.epa.gov/waterscience/standards/.
After setting water quality standards, states assess their waters to determine the degree to
which the standards are being met. State water quality assessments are normally based on six
broad types of monitoring data: biological integrity, chemical, physical, microbiological, habitat,
and toxicity. (Examples of the different types of data used to determine a state's water quality are
shown in the box below.) Each type of monitoring data yields an assessment that must be
integrated with other data types for an overall assessment. Depending on the designated use, one
data type may be more informative than others for making the final assessment.
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National Water Quality Inventory: 2004 Report to Congress
Types of Monitoring Data
• Biological integrity data: Objective measurements of aquatic biological communities (usually
aquatic insects, fish, or algae) used to evaluate the condition of an aquatic ecosystem. Biological
data are best used when deciding whether waters support aquatic life uses.
• Chemical data: Measurements of key chemical constituents in water, sediments, and fish tissue.
Examples of these constituents include metals, oils, pesticides, and nutrients such as nitrogen
and phosphorus. Monitoring for specific chemicals helps states assess waters against numerical
criteria, as well as identify and trace the source of the impairment.
• Physical data: Characteristics of water, such as temperature, flow, suspended solids, sediment,
dissolved oxygen, and pH. These physical attributes are often useful indicators of potential
problems and can have an effect on the impacts of pollution.
• Microbiological data: Measurements of pathogen indicators such as fecal and total coliform
bacteria, E.coli and Enterococci. Monitoring of these indicators helps determine possible
contamination by such things as untreated sewage, septic systems, and livestock or pet wastes,
and is often used to determine if waters are safe for recreation and shellfish harvesting.
• Habitat assessments: Descriptions of sites and surrounding land uses; condition of streamside
vegetation; and measurement of features, such as stream width, depth, flow, and substrate.
These assessments are used to supplement and interpret other kinds of data.
• Toxicity testing: Measurements of mortality of a test population of selected organisms, such as
fathead minnows or Daphnia ("water fleas"). These organisms are exposed to known dilutions of
water taken from the sampling location. The resulting toxicity data indicate whether an aquatic life
use is being attained. These tests can help determine whether poor water quality results from
toxins or from habitat degradation.
States, tribes, and other jurisdictions monitor for a variety of pollutants, or causes of
impairment. Table 1 provides a list of major causes of impairment cited in this report.
Table 1. Major Impairment Cause Categories Used in this Report
Category
Cause Unknown -
Impaired Biota
Dioxins
Flow Alterations
Habitat Alterations
Metals
Mercury
Nuisance Exotic Species
Nutrients
Organic Enrichment/
Oxygen Depletion
Examples
Impairment or degradation of the biological community (e.g. fish,
macroinvertebrates) due to unknown/unidentified cause
Highly toxic, carcinogenic, petroleum-derived chemicals that are persistent in the
environment and may be found in fish tissue, water column, or sediments
Changes in stream flow due to human activity; includes water diversions for purposes
such as irrigation
Modifications to substrate, streambanks, fish habitat; barriers
Substances identified only as "metals;" also, selenium, lead, copper, arsenic,
manganese, others (Note: may, in some cases, include mercury)
A toxic metal with neurological and developmental impacts; found in fish tissue,
water column, or sediments
Non-native fish, animals, or plants such as Eurasian milfoil, Hydrilla, or zebra
mussels, which choke out native species and alter the ecological balance of waters
Primarily nitrogen and phosphorus; in excess amounts, these nutrients overstimulate
the growth of weeds and algae and can lead to oxygen depletion
Low levels of dissolved oxygen; high levels of biochemical oxygen demanding
substances (e.g., organic materials such as plant matter, food processing waste,
sewage) that use up dissolved oxygen in water when they degrade
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National Water Quality Inventory: 2004 Report to Congress
Category
Pathogens
Polychlorinated
biphenyls (PCBs)
Pesticides
Sediment
Toxic Organics
Examples
Bacteria and pathogen indicators E.coli, total coliforms, fecal coliforms, Enterococci;
used as indicators of possible contamination by sewage, livestock runoff, and septic
tanks
A toxic mixture of chlorinated chemicals that are no longer used, but are persistent in
the environment; used originally in industry and electrical equipment; primarily
found in fish tissue or sediments
Substances identified only as "pesticides;" also, chlordane, atrazine, carbofuran, and
others; many older pesticides are persistent in the environment
Excess sediments, siltation; affects aquatic communities by altering and suffocating
habitat and clogging fish gills
Chemicals identified only as "toxic organics;" also, priority organic compounds, non-
priority organic compounds, polycyclic aromatic hydrocarbons (PAH), and others;
often persistent in the environment
Where possible, states, tribes, and other jurisdictions identify the sources of those
pollutants associated with water quality impairment. Point sources discharge pollutants directly
into surface waters from a conveyance, such as a pipe. Point sources include industrial facilities,
municipal sewage treatment plants, combined sewer overflows, and storm sewers. Nonpoint
sources deliver pollutants to surface waters from diffuse origins, such as fields and streets.
Nonpoint sources include urban runoff that is not captured in a storm sewer; agricultural runoff
from cropland and grazing areas; leaking septic tanks; and deposition of contaminants in the
atmosphere due to air pollution. Habitat alterations, dams, channelization, dredging, and stream
bank destabilization are also significant sources of water quality degradation. See Table 2 for
more information on source categories used in this report.
For 2004 reporting, EPA reorganized many source categories compared to previous
reporting cycles; therefore, apparent significant increases or decreases in individual categories
(e.g., Municipal Discharges/Sewage) may be attributable to these reporting changes rather than
to actual changes in the impact of an individual source category.
Table 2. Major Pollutant Source Categories Used in this Report
Category
Agriculture
Atmospheric Deposition
Construction
Habitat Alterations (Not
Directly Related to
Hydromodification)
Hydromodification
Industrial
Examples
Crop production, feedlots (including concentrated animal feeding operations),
grazing, manure runoff
Airborne pollution from many diverse sources (such as factory and automobile
emissions and pesticide applications) that settles to land or water
Residential development, bridge and road construction, land development
Riparian and in-stream habitat modification and loss, filling and draining of
wetlands, removal of riparian vegetation, streambank erosion
Pond construction, channelization, dam construction, dredging, flow alterations
from water diversions, flow regulation, hydropower generation, streambank
destabilization and modification, upstream impoundments
Factories, industrial and commercial areas, cooling water intake structures, mill
tailings
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National Water Quality Inventory: 2004 Report to Congress
Category
Land Application/Waste
Sites/Tanks
Legacy /Historical Pollutants
Municipal
Discharges/Sewage
Natural/Wildlife
Recreation and Tourism
Resource Extraction
Silviculture (Forestry)
Spills/Dumping
Unknown
Unspecified Nonpoint Source
Urban-Related
Runoff/Stormwater
Examples
Salt storage piles, land application of biosolids, land disposal, landfills, leaking
underground storage tanks
Brownfield sites, contaminated sediments, in-place contaminants
Septic systems, sewage treatment plants, domestic sewage lagoons, sanitary
sewer overflows, municipal dry and wet weather discharges, unpermitted
discharges of domestic wastes, combined sewer overflows, septage disposal
Flooding, drought-related impacts, waterfowl
Golf courses, marinas, turf management, boat maintenance
Abandoned mining, acid mine drainage, coal mining, dredge mining,
mountaintop mining, petroleum/natural gas activities, surface mining
Forest management, forest fire suppression, forest roads, reforestation, woodlot
site clearance
Accidental releases/spills, pipeline breaks
Source of impairment is unknown
Source of impairment is identified as nonpoint, but no further information
available
Discharges from municipal separate storm sewers (MS4), parking lot and
impervious surfaces runoff, highway and road runoff, storm sewers, urban
runoff, permitted stormwater discharges
Hundreds of organizations in the United States conduct water quality monitoring.
Monitoring organizations include state, interstate, tribal, and local water quality agencies;
research organizations such as universities; industries and sewage and water treatment plants;
and citizen volunteer programs. EPA, the U.S. Geological Survey (USGS), the National Park
Service (NPS), and the National Oceanic and Atmospheric Administration (NOAA) are among
the many federal agencies that collect water quality monitoring data. Monitoring organizations
collect water quality data for their specific purposes, and many share their data with other users,
including government decision makers. States evaluate and use much of these data when
preparing their water quality reports.
The states, territories, and tribes maintain monitoring programs to support several
objectives, including assessing whether water is safe for drinking, swimming, and fishing. States
also use monitoring data to review and revise water quality standards, identify impaired and
threatened waters under Clean Water Act section 303(d), develop pollutant-specific TMDLs,
determine the effectiveness of control programs, adjust drinking water treatment requirements,
measure progress toward clean-water goals, and respond to citizen complaints or events such as
spills and fish kills.
Nationally consistent probability surveys are an efficient way to get a good understanding
of national water quality conditions and trends. Probability surveys are scientifically based
studies designed to sample water quality conditions at randomly selected sites that are
statistically representative of the population of waters across the United States. EPA and its
monitoring partners have used this methodology to develop a series of National Coastal
Condition Reports (http ://www. epa.gov/nccr/). These reports summarize the findings of the
National Coastal Assessment, a probability-based study. Another probability-based project
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National Water Quality Inventory: 2004 Report to Congress
currently underway is the National Study of Chemical Residues in Lake Fish Tissue
(www.epa.gov/waterscience/fishstudy), which is the first national freshwater fish contamination
survey to have statistically selected sampling sites. EPA also partnered with states to conduct a
probability-based Wadeable Streams Assessment (www. epa. gov/o wow/stream survey) to
determine the biological condition of small streams in the United States. The Wadeable Streams
Assessment was completed in 2006.
To learn more about the water quality monitoring, assessment, and reporting practices of a specific
state, visit the state's water quality Internet site and read the explanatory and programmatic
information included in most reports.
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National Water Quality Inventory: 2004 Report to Congress
II. Findings
Rivers and Streams
The 2004 ATTAINS database summarizes river and stream designated use support
information reported by the states by overall use support and by individual categories of uses.
Waters are rated for overall use support as follows:
• Good if they fully support all their designated uses
• Threatened if they fully support all uses, but exhibit a deteriorating trend
• Impaired if they are not supporting one or more designated uses.
This report includes states' 2004 assessments of 563,955 miles of rivers and streams, or
16% of the nation's 3.5 million stream miles (Figure 1). Because six states did not provide
specific waterbody data electronically in 2004, the findings of this report address about 130,000
fewer stream miles than were reported in 2002. States identified 44% of the assessed miles as
being impaired, or not supporting one or more of their designated uses. The remaining 56% of
assessed miles fully supported all uses, and of these, 3% were considered threatened (i.e., water
quality supported uses, but exhibited a deteriorating trend).
Total U.S. Streams
3,533,205 Miles
84%
Unassessed
Assessed Streams
563,955 Miles
3% Good but
Threatened
15,698 Miles
302,255
Miles ^^^^^^^
W 246,002 Miles
'Total U.S. river and stream miles based on state 2004 Integrated Reports.
Percents may not add up to 100 because of rounding.
Figure 1. Water quality in assessed river and stream miles.
Individual use support assessments also provide important details about the nature of
water quality problems in rivers and streams. Table 3 shows the top five assessed uses in rivers
and streams. States evaluated support of the Fish, Shellfish, and Wildlife Protection and
Propagation use most frequently, assessing a total of 466,617 stream miles (or 13% of U.S.
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National Water Quality Inventory: 2004 Report to Congress
stream miles) and reporting that 36% of assessed stream miles were impaired for this use. States
assessed 303,317 stream miles for Recreation uses (primary and secondary contact) and found
recreation to be impaired in 28% of these waters.
Table 3. Individual Use Support in Assessed River and Stream Miles3
Designated Use
Fish, Shellfish, and Wildlife
Protection/Propagation
Recreation
Agricultural
Aquatic Life Harvesting
Public Water Supply
Miles
Assessed
466,617
303,317
200,817
154,746
144,245
Percentage
of Total U.S.
River Miles
13
9
6
4
4
Percentage of Waters Assessed
Good
61
69
90
56
79
Threatened
3
o
5
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National Water Quality Inventory: 2004 Report to Congress
Miles
Pathogens
Habitat Alteration
Organic Enrichment or
Oxygen Depletion
Cause Unknown-Impaired Biota
Nutrients
Metals
Sediment
Mercury
Flow Alteration
Turbidity
5 10 15 20 25 30 35
Percent of Impaired Stream Miles Affected
Note: Percents do not add up to 100% because more than one cause may impair a waterbody.
Figure 2. Top 10 causes of impairment in assessed rivers and streams.
The listed top 10 causes of impairment (above) differ from those reported in 2002. This
difference is more likely attributable to reporting changes (e.g., fewer river and stream miles
assessed; improved reporting of the results of I
fish tissue monitoring; and administrative More detailed information on state-reported
changes in cause category definitions, causes and sources of impairment is available
, ., , , s ., . . . . . from the ATTAINS Water Quality Assessment and
described above) than to actual changes in TMDL |nformation database at
water quality. http://www.epa.gov/ir.
Figure 3 shows the top reported sources
of impairment in assessed rivers and streams. According to the states, the top sources of river and
stream impairment included the following:
• Agricultural activities, such as crop production, grazing, and animal feeding operations;
• Hydromodifications, such as water diversions, channelization, and dam construction;
and
• Unknown or unspecified sources (i.e., the states could not identify specific sources).
Other leading sources of impairment in streams included habitat alteration (e.g., loss of
streamside habitat), natural sources (e.g., floods, droughts, wildlife), municipal
discharges/sewage (which includes sewage treatment plant discharges and combined sewer
overflows), and unspecified nonpoint sources.
15
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National Water Quality Inventory: 2004 Report to Congress
Miles
Agriculture
Hydromodification
Unknown
Habitat Alteration
Natural/Wildlife
Municipal Discharges/Sewage
Unspecified Nonpoint Source
Atmospheric Deposition
Resource Extraction
Urban Runoff/Stormwater
40
45
10 15 20 25 30 35
Percent of Impaired Stream Miles Affected
Note: Percents do not add up to 100% because more than one source may impair a waterbody.
Figure 3. Top 10 sources of impairment in assessed rivers and streams.
Lakes, Ponds, and Reservoirs
The 2004 ATTAINS Water Quality Assessment and TMDL Information database
summarizes designated use support information reported by the states for lakes, ponds, and
reservoirs (referred to hereafter as lakes) by overall use support and by individual categories of
uses.
This report includes states' assessments of 16.2 million acres of lakes (excluding the
Great Lakes), or 39% of the nation's total 41.7 million lake acres, for the 2004 reporting cycle
(Figure 4). States identified 64% of assessed acres as impaired, or not supporting one or more of
their designated uses (such as fishing or swimming). The remaining 36% of assessed acres fully
supported all uses, and of these, 1% were considered threatened. It should be noted that 3.7
million impaired lake acres—about a third of all impaired lake acres— were reported by one
state, Minnesota, due to increased fish tissue and water monitoring activities addressing mercury.
16
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National Water Quality Inventory: 2004 Report to Congress
Total U.S. Lakes
41,666,049 Acres
61%
Unassessed
25,435,665
Assessed Lakes
16,230,384 Acres
1% Good but
Threatened
159,761 Acres
5,619,221
Acres
^H r~'W
10,451,402
Acres
'Total U.S. lake acreage estimate based on 2004 state Integrated Reports.
Figure 4. Water quality in assessed lake acres.
Individual use support assessments provide important details about the nature of water
quality problems in lakes and reservoirs. Table 4 shows the top five uses assessed in lakes,
ponds, and reservoirs. States assessed 11.8 million lake acres for support of the Fish, Shellfish,
and Wildlife Protection and Propagation use, of which 30% were found to be impaired. The
Aquatic Life Harvesting use (primarily fish consumption) was assessed in 9.4 million acres; of
these, 73% were impaired and 1% were considered threatened (i.e., water quality is
deteriorating). This high percentage of lake, pond, and reservoir waters impaired for fish
consumption is most likely related to changes in how states report on waters with statewide fish
consumption advisories. For example, in previous cycles, some states may not have reported
waters with fishing advisories as impaired. Recreational use (e.g., swimming, boating) was
assessed in 8.1 million acres of lakes and found to be impaired in 26%.
Table 4. Individual Use Support in Assessed Lake, Reservoir, and Pond Acres3
Designated Use
Fish, Shellfish, and Wildlife
Protection/Propagation
Aquatic Life Harvesting
Recreation
Public Water Supply
Industrial
Acres
Assessed
11,770,370
9,390,396
8,069,018
6,427,687
2,848,335
Percentage
of Total U.S.
Lake Acres
28%
23%
19%
15%
7%
Percentage of Waters Assessed
Good
66%
26%
70%
78%
82%
Threatened
4%
1%
4%
1%
<1%
Impaired
30%
73%
26%
20%
17%
1 Waterbodies can have multiple designated uses, resulting in an overlap of acres assessed.
17
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National Water Quality Inventory: 2004 Report to Congress
The ATTAINS database provides more detailed information on the sources and causes of
impairments in lakes, but it is important to note that the information about specific sources and
causes of impairment is incomplete. The states do not always report the pollutant or source of
pollutants affecting every impaired lake, pond, and reservoir. In some cases, states may
recognize that water quality does not fully support a designated use; however, they may not have
adequate data to document the specific pollutant or source responsible for the impairment. The
states may then simply report the cause or source of impairment as "unknown" or "unspecified."
It is also important to note that, in some cases, groupings of causes and sources may have
changed since previous reporting cycles. These changes were made to more accurately
categorize the source and cause information reported by the states.
Figure 5 shows the top causes of impairment in assessed lakes, ponds, and reservoirs.
According to the states, the top causes of lake impairment were the following:
• Mercury, which has been widely detected in fish tissue, where it may pose a health risk
to people and animals who eat fish;
• PCBs, which are hazardous chemicals released via industrial and municipal waste
disposal, spills, and leaks; and
• Nutrients, such as phosphorus and nitrogen, which disrupt lake ecosystems by
stimulating growth of undesirable algae and aquatic weeds.
Acres
Mercury
PCBs
Nutrients
Metals
Organic Enrichment or
Oxygen Depletion
Nuisance Exotic Species
Sediment
Pathogens
Turbidity
Other Cause
5,890,915
2,344,542
1,952,386
1,517,163
1,214,301
960,884
623,270
528,425
509,906
494,221
10 IS 20 25 30 35 40 45 50 55 60 65
Percent of Impaired Lake Acres Affected
Note: Percents do not add up to 100% because more than one cause may impair a waterbody.
Figure 5. Top 10 causes of impairment in assessed lakes, ponds, and reservoirs.
Heightened reporting of mercury, PCBs, and metals is largely the result of the reporting
of broad-based fish consumption advisories due to these substances in fish tissue; some states
have begun reporting the extent of waters affected by such advisories and bans. For example,
18
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National Water Quality Inventory: 2004 Report to Congress
Minnesota reported 3.7 million acres impaired by mercury (representing 63% of the lake acres
impaired by mercury in the United States) and 1.6 million acres impaired by PCBs (representing
70% of the lake acres impaired by PCBs in the
United States). Other leading causes of
impairments in lakes include organic
enrichment/low dissolved oxygen, fish
consumption advisory/pollutant unspecified,
nuisance exotic species, sediment, turbidity,
and pathogens.
More information on state-re ported causes and
sources of impairment is available from the
ATTAINS Water Quality Assessment and TMDL
Information database at
http ://www.epa.gov/waters/ir.
Figure 6 shows the top sources of impairment in assessed lakes, ponds, and reservoirs.
According to the states, the top sources of lake impairment were the following:
• Atmospheric (or air) deposition, primarily of toxic substances such as mercury, PCBs,
and other metals, from both local and long-range sources;
• Unknown or unspecified sources (i.e., the states could not identify specific sources);
and
• Agricultural activities, such as crop production and grazing.
Acres
Atmospheric Deposition
Unknown
Agriculture
Natural/Wildlife
Hydromodification
Urban Runoff/Stormwater
Municipal Discharges/Sewage
Legacy/Historical Pollutants
Resource Extraction
Unspecified Nonpoint Source
0 5 10 IS 20 25
Percent of Impaired Lake Acres Affected
Note: Percents do not add up to 100% because more than one source may impair a waterbody.
Figure 6. Top 10 sources of impairment in assessed lakes, ponds, and reservoirs.
It should be noted that about one fourth (485,376 acres) of lake acres impaired by
atmospheric deposition were reported by one state, Wisconsin. This is because Wisconsin
reported that all its lake acres are under a fish consumption advisory due to mercury from
atmospheric deposition sources. However, the total does not include lake acres that may be
impaired by atmospheric deposition in Minnesota, which reported the largest number of impaired
lake acres for mercury and PCBs, because Minnesota did not identify the source of these
2,009,363
1,988,588
1,670,513
1,256,542
1,248,432
701,024
583,211
521,250
490,638
485,585
19
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National Water Quality Inventory: 2004 Report to Congress
impairments. It is likely that the majority of impairment by mercury and PCBs in Minnesota is
from atmospheric deposition. Other leading sources of impairment include natural/wildlife
sources (e.g., droughts, flooding, waterfowl), hydromodification, urban-related
runoff/stormwater, municipal discharges/sewage, and legacy/historical pollutants (primarily in
sediments).
Bays and Estuaries
The ATTAINS database summarizes state-reported designated use support information
for bays and estuaries by overall use support and by individual categories of uses.
This report includes states' assessments of 25,399 square miles of bays and estuaries, or
29% of the nation's total estimated 87,791 square miles, for the 2004 reporting cycle (Figure 7).
About 5,000 fewer estuarine square miles were assessed in 2004 than in 2002, at least in part
because several coastal states did not provide electronic data in 2004. States identified 30% of
assessed square miles as impaired, or not supporting one or more of their designated uses (e.g.,
swimming, fishing, shellfishing). The remaining 70% of assessed estuarine square miles were
fully supporting all uses.
Total U.S. Bays and Estuaries
87,791 Square Miles
71%
Unassessed
62,392
Square Miles ^^^^^^^^_
Assessed Bays and Estuaries
25,399 Square Miles
<\% Good but
17,721 • 3Q% •/ Threatened
Square Miles , "'.' ' 37 Square Miles
30% fr
Impaired
7,641
Square Miles
Total U.S. estuarine square miles estimate based on 2004 state Integrated Reports.
Figure 7. Water quality in assessed bay and estuary square miles
Individual use support assessments provide important details about the nature of water
quality problems in bays and estuaries. Table 5 shows the top three uses assessed in bays and
estuaries. States assessed 24,338 estuarine square miles for support of the Fish, Shellfish, and
Wildlife Protection and Propagation use and found that 27% were impaired; the Aquatic Life
Harvesting use was assessed in 11,004 square miles and found to be impaired in 19% of assessed
20
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National Water Quality Inventory: 2004 Report to Congress
waters; and 13% of the 9,322 square miles assessed for Recreation uses (e.g., swimming,
boating) were reported as impaired.
Table 5. Individual Use Support in Assessed Bay and Estuary Square Miles a
Designated Use
Fish, Shellfish, and Wildlife
Protection/Propagation
Aquatic Life Harvesting
Recreation
Square Miles
Assessed
24,338
11,004
9,322
Percentage
of Total U.S.
Estuarine
Miles
28%
13%
11%
Percentage of Waters Assessed
Good
73%
81%
87%
Threatened
<1%
<1%
<1%
Impaired
27%
19%
13%
a Waterbodies can have multiple designated uses, resulting in an overlap of square miles assessed.
State-reported information about specific sources and causes of impairment may be
incomplete because the states do not always report the pollutant or source of pollutants affecting
every impaired bay and estuary. In some cases, states may recognize that water quality does not
fully support a designated use; however, they may not have adequate data to document the
specific pollutant or source responsible for the impairment and report the cause or source as
"unknown."
Figure 8 shows the top causes of impairment in assessed bays and estuaries. According to
the states, the top causes of estuarine impairment were the following:
• Pathogens, i.e., bacteria used as indicators of possible contamination by sewage,
livestock runoff, and other sources;
• Organic enrichment/oxygen depletion, i.e., low levels of dissolved oxygen and/or high
levels of oxygen-demanding substances such as organic waste; and
• Mercury, a toxic metal found in fish tissue, and, to a lesser extent, in the water column,
often entering the aquatic environment via atmospheric deposition.
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National Water Quality Inventory: 2004 Report to Congress
Square Miles
Pathogens
Organic Enrichment or
Oxygen Depletion
Mercury
Toxic Organics
Nutrients
Pesticides
Habitat Alteration
PCBs
Metals
Turbidity
0
20
2,845
2,180
1,700
1,441
1,047
1,041
692
665
654
637
5 10 15 20 25 30 35 40
Percent of Impaired Estuary Square Miles Affected
Note: Percents do not add up to 100% because more than one cause may affect a waterbody.
Figure 8. Top 10 causes of impairment in assessed bays and estuaries.
Toxic organics, nutrients, pesticides, and metals are also reported as top causes of
impairment for estuarine waters.
Figure 9 shows the top sources of impairment in assessed bays and estuaries. According
to the states, the top sources of estuarine impairment included the following:
• Atmospheric (or air) deposition, which can bring pollutants such as mercury from
distant locations such as industrial centers;
• Unknown/unspecified sources, or sources
that cannot be further identified by the
states; and
• Municipal discharges/sewage, which
includes septic systems, sewage treatment
plants, and sanitary and combined sewer
overflows.
More information on state-reported causes
and sources of impairment is available from
the ATTAINS Water Quality Assessment and
TMDL Information database at
http://www.epa.gov/waters/ir.
Other leading sources of impairment in bays and estuaries were unspecified nonpoint
sources, other sources (such as sources outside state waters), and industrial sources.
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National Water Quality Inventory: 2004 Report to Congress
Square Miles
Atmospheric Deposition
Unknown
Municipal Discharges/Sewage
Unspecified Nonpoint Source
Other
Industrial
Natural/Wildlife
Urban Runoff/Stormwater
Agriculture
Hydromodification
0 5 10 15 20 25 30 35 40 45
Percent of Impaired Estuary Square Miles Affected
Note: Percents do not add up to 100% because more than one source may impair a waterbody.
Figure 9. Top 10 sources of impairment in assessed bays and estuaries.
Other Waters
The 2004 ATTAINS database also contains state-reported information on conditions in
coastal shoreline waters, ocean waters, Great Lakes, and wetlands, although, in some cases, only
a small percentage of these resources were assessed in the 2004 reporting cycle. These waters are
discussed below.
Coastal Resources
Coastal resources are identified in the ATTAINS database in two categories: coastal
shorelines (the water immediately offshore, reported in miles) and ocean/near-coastal waters
(i.e., the area of water extending into the ocean or gulf, range not specified, in square miles).
Eight states assessed 1,859 miles of coastal shorelines, or about 3% of the nation's total 58,618
shoreline miles. The majority of assessed shoreline miles (68%) fully support their designated
uses, with 12% of these miles classified as supporting uses, but threatened (i.e., water quality is
deteriorating). In the 32% of shoreline miles not fully supporting their uses, metals (which could
in some cases include mercury) and pathogens were the leading causes of impairment, and
municipal discharges/sewage and industrial sources were listed as top sources of impairment.
To help protect the public at coastal recreation waters, Congress passed the Beaches
Environmental Assessment and Coastal Health Act of 2000 (BEACH Act), requiring that coastal
and Great Lakes states and territories report to EPA on beach monitoring and notifications to the
public of potential health risks. Public notification may include issuing a beach advisory,
warning people of possible risks of swimming due to water quality problems, or closing a beach
to the public. The BEACH Act also requires EPA to maintain an electronic monitoring and
notification database of those data.
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National Water Quality Inventory: 2004 Report to Congress
For the 2004 swimming season, 28 of 30 coastal states and Puerto Rico reported public
notification actions to EPA. Of the 3,574 beaches that were monitored in 2004, 942 (26%) had at
least one advisory or closing. A total of 4,907 beach notification actions were reported. EPA
calculates "beach days" (number of beaches multiplied by number of days in the swimming
season) to get a better sense of the extent of the advisory and closure information. For the 2004
season, EPA determined that there were 584,150 beach days for all of the monitored beaches,
and actions were reported about 4% of the time. EPA is continuing to work to improve the
delivery of its beach advisory information to the public. Visit http://www.epa.gov/beaches/ for
more information on beach monitoring and notification.
A total of 5,544 square miles of oceans and near-coastal waters, or 10% of approximately
54,120 square miles of oceans and near-coastal waters in the United States, were assessed by 5
states in 2004. Of the assessed square miles, 88% were identified as impaired. Mercury was by
far the most commonly reported cause of
impairment, followed by organic
More information on state-reported causes and
sources of impairment is available from the
ATTAINS database information website at
http://www.epa.gov/waters/ir..
enrichment/oxygen depletion. Atmospheric
deposition was the predominant reported
source of impairment in oceans and near-
coastal waters. (It is important to note that
Texas alone assessed nearly 3,879 square
miles of oceans and near-coastal waters and reported that 100% of its assessed square miles are
impaired due to mercury in fish tissue from atmospheric deposition.)
Detailed information on U.S. coastal condition trends is available in the EPA's National
Coastal Condition Report series, which presents the findings of a collaborative effort between
the states, EPA, and other federal agencies to characterize the condition of 100% of the nation's
coastal resources. Section III of this report summarizes key findings of the draft National
Coastal Condition Report III.
Great Lakes
The Great Lakes—Superior, Michigan, Huron, Erie, and Ontario—are freshwater inland
seas of vast importance for water consumption, recreation, fisheries, power, transportation, and
many other uses. Of the eight states bordering the Great Lakes, six reported on the condition of
their Great Lakes shoreline miles.
About 1,070 of 5,521 total Great Lakes shoreline miles were assessed in 2004, and of
these, 93% were reported as impaired. The leading causes of impairment included PCBs, toxic
organics, pesticides, and dioxins. Legacy or historical pollution—primarily contaminated
sediment—were the leading source of shoreline impairment reported by the states, followed by
municipal discharges/sewage.
Wetlands
Wetlands occur where water and land come together for a prolonged period of time and
where saturation of the land with water is the dominant factor determining soil types and the
plant and animal communities living in the soil and on the surface. Wetlands vary widely
24
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National Water Quality Inventory: 2004 Report to Congress
because of regional and local differences in soils, topography, climate, hydrology, water
chemistry, vegetation, and other factors, including human disturbance. Included among the many
types of U.S. wetlands are marshes, bogs, swamps, wet meadows, vernal pools, playas, pocosins,
sloughs, peat lands, prairie potholes, and fens.
Wetlands are a critically important resource due to the many benefits they provide to
humans, aquatic life, wildlife, and the environment. Wetlands produce great quantities of food
that attract a huge variety of animal species. They serve as nurseries and habitat for many game
and commercial fish and wildlife species, and they help improve water quality by intercepting
surface runoff and removing, retaining, or filtering out a broad range of substances (e.g.,
nutrients, sediments, organic wastes). By storing and slowly releasing water, wetlands help
reduce the impacts of floods and erosion, as well as help replenish groundwater and stream flow
during dry periods. Wetlands are also of great recreational value to bird watchers, hunters,
fishermen, and nature lovers.
Only 10 states provided information on the support of designated uses for 1.8 million
acres of wetlands assessed in their 2004 reports—a tiny portion of the nation's estimated 107
million acres. States identified 30% of these assessed acres as impaired. Organic
enrichment/oxygen depletion, sediment, and turbidity were the leading causes of wetland
degradation in these six states. Agriculture, unknown/unspecified sources, and atmospheric
deposition were listed by the states as top contributors to impairment.
Section III of this report discusses plans for an upcoming National Wetland Condition
Assessment.
25
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National Water Quality Inventory: 2004 Report to Congress
III. Probability Surveys of Water Quality
EPA, other federal agencies, and the states have embarked on a cost-effective approach to
assess status and track trends in the quality of the nation's waters: probability-based surveys that
complement existing monitoring and assessment programs and add to our understanding of
national, regional, and local water quality conditions. Probability surveys are designed to yield
unbiased estimates of the condition of a whole resource (such as lakes or rivers and streams)
based on a representative sample of waters. These surveys are designed to answer key questions
asked by Congress, the public, and decision makers, such as
• Is water quality improving?
• What is the extent of waters that support healthy ecosystems, recreation, and fish
consumption?
• How widespread are the most significant water quality problems?
• Are we investing in restoration and protection wisely?
Several national probability-based studies have already been completed, and several more
are underway.
Understanding the Value of Probability-based Surveys and the National 305(b) Report
Although some of the findings of the national 305(b) report appear similar to the findings of the
national, probability-based coastal and streams surveys, there are many differences in the scope of
these reports and how they are best used to inform water quality management.
Probability surveys provide consistent environmental indicators of the condition of the nation's water
resources, much as economic indicators report on the health of the nation's economy. Their design
ensures that results represent the population of all waters of a certain type across the United States,
and their consistent sampling methods ensure that results can be aggregated into regional and
national indicators of the health of the resource. The survey results quantify, with documented
confidence, how widespread water quality problems are across the country and estimate the extent of
waters affected by key stressors. This helps set priorities for water resource protection and restoration.
Nationally consistent surveys provide a standardized measure for tracking changes in the condition of
the nation's waters over time and for evaluating, at a broad scale, progress in investments to protect
and restore water quality.
In contrast to the probability surveys, this national 305(b) report summarizes information reported by
states for only a portion of waters (approximately 16% of U.S. river and stream miles, 39% of lake
acres, and 29% of bay and estuarine square miles). It tallies state findings based on data collected
using a variety of sampling methods and parameters; water quality standards and interpretation
methods; extrapolation methods; and time periods. The strength of the 305(b) report is that it provides
useful information on the nature of water quality problems identified by state monitoring programs;
documents the amount of waters assessed and unassessed; and supports the identification of specific
waters not meeting water quality standards; therefore, it helps states set priorities for these waters.
National Coastal Assessment
The National Coastal Assessment surveys the condition of the nation's coastal resources.
The results of these surveys have been compiled into the National Coastal Condition Report
26
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National Water Quality Inventory: 2004 Report to Congress
series. The states, EPA, and partner agencies — NOAA, USGS, and the U.S. Fish and Wildlife
Service (FWS) — issued the first three reports of the National Coastal Condition Report series
in 2001, 2005, and 2008. These reports include evaluations of 100% of the nation's estuaries in
the contiguous 48 states and Puerto Rico. Federal, state, and local agencies collected samples
using nationally consistent methods and a probability-based design to assess five key indices of
coastal water health.
The National Coastal Condition
Report III finds that the overall
condition of the nation's coastal waters
is generally fair and has improved
slightly since the 1990s. This rating is
based on five indices of ecological
condition: a water quality index
(calculated based on ratings for
dissolved oxygen, chlorophyll a,
dissolved inorganic nitrogen, dissolved
inorganic phosphorus, and water
clarity), a sediment quality index
(calculated based on ratings for
sediment toxicity, sediment
contaminants, and sediment total
organic carbon), a benthic index, a
coastal habitat index, and a fish tissue
contaminants index. For each of these
indicators, a score of good, fair, or poor
was assigned to each coastal region of
Overall Condition
U.S. Coastal Waters
Figure 10. Findings of the National Coastal
Condition Report III (U.S. EPA, 2008).
the United States. Ratings were then averaged to create the overall regional and national scores
illustrated in Figure 10, which uses "traffic light" color scoring. Based on the findings of this
survey, fifty-seven percent of the area of the nation's estuaries and coastal embayments are in
good condition for the water quality index, 6% are in poor condition, and 35% are in fair
condition.
The indices that show the poorest condition are coastal habitat and benthic condition.
Two of the individual component indicators of the water quality index generally show the best
condition —dissolved oxygen and dissolved inorganic nitrogen.
In 2010, EPA and its partners expect to undertake a new survey of coastal waters and
expect to report survey results in 2012. For more information on the National Coastal Condition
Report series, go to http://www.epa.gov/nccr/.
The Wadeable Streams Assessment
The Wadeable Streams Assessment, a survey of the biological health of the nation's
wadeable streams, was launched by EPA and the states to provide a national baseline of stream
water quality based on conditions at approximately 1,300 randomly selected sites across the
conterminous United States. With support from EPA, state water quality agencies sampled
27
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National Water Quality Inventory: 2004 Report to Congress
,2.0%
9.5%
Plains and Lowlands
242,264 miles
Eastern Highlands
276,362 miles
National
Biological Condition
5.0%
streams using the same methods at all sites. Crews collected macroinvertebrates to determine the
biological condition of streams. They also measured key chemical and physical indicators that
reveal stress or degradation of streams. The Wadeable Streams Assessment reports on four
chemical indicators (i.e., phosphorus, nitrogen, salinity, and acidity) and four physical condition
indicators (i.e., streambed sediments, in-stream fish habitat, riparian vegetative cover, and
riparian
disturbance).
The
Wadeable Streams
Assessment found
that 42% of U.S.
stream miles are in
poor biological
condition compared
to best-available
reference sites in
their ecological
regions, 25% are in
fair condition, and
28% are in good
condition (Figure
11). The confidence
level for these key
findings of
biological quality is
±2.8%. Five percent
of U.S. stream miles
were not assessed
because the New
England states did
not include first
order streams in the
sample design.
• Good
D Fair
• Poor
D Not Assessed
Figure 11. Biological quality of the nation's streams
(U.S. EPA, 2006).
Extent of Stressor
Relative Risk to
Biological Condition
The study was
designed to examine
eight key stressors.
The most widespread
stressors observed
across the country and
in each of the three
major regions are
nitrogen, phosphorus,
riparian disturbance,
and streambed
sediments (Figure 12).
Nitrogen
Phosphorus
Riparian Disturbance
Streambed Sediments
In-stream Fish Habitat
Riparian Vegetative Cover
Salinity
Acidification
h-H 3 1.8%
FpH 30.9%
h-H «.5%
h-H 24.9%
1 119.5%
1 119.3%
_jji 2.9%
~2.2%
1 1 111
h-H 12.2
h-H 1.4
1 1 12.4
1— Hi. 4
h-H 1.6
h-| Hi. 7
10
20
30
40
Percentage Stream Length in Most
Disturbed Condition
2 3
Relative Risk
Figure 12. Extent of streams rated poor for aquatic stressors, and
increase in risk of poor biology in streams rated poor over streams
rated good for each stressor (U.S. EPA, 2006).
28
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National Water Quality Inventory: 2004 Report to Congress
These stressors can degrade stream conditions for fish and other aquatic life. Nitrogen and
phosphorus are nutrients that, when present in excess amounts, can increase the growth of algae,
decrease levels of dissolved oxygen and water clarity, and degrade stream habitat. Excess
streambed sediments can smother habitat for aquatic organisms. Riparian disturbance is evidence
of human activity alongside streams, such as pipes, pavement, and pastures. The survey found
that increases in nutrients and streambed sediments have the highest impact on biological
condition, i.e., streams scoring poor for these stressors are twice as likely to have poor biological
condition as streams that score in the good range for the same stressors. For more information on
the Wadeable Streams Assessment, go to http://www.epa.gov/owow/streamsurvey.
Survey of the Nation's Lakes
NLA sample site
NLA and NES sample site
In 2007, EPA and
its state partners completed
the field sampling season
for the Survey of the
Nation's Lakes, a baseline
assessment of the condition
of the nation's lakes,
ponds, and reservoirs. More
than 900 lakes were
sampled over the course of
a summer for this survey
(see Figure 13). The
population of lakes to be
sampled was comprised of
natural and man-made
freshwater lakes, ponds,
and reservoirs that were
greater than 10 acres, at
least one meter in depth,
and located in the conterminous United States. The survey does not include the Great Lakes, the
Great Salt Lake, natural saline systems, or treatment and disposal ponds. In order to examine
potential trends in water quality, a representative subset of lakes from EPA's 1972 National
Eutrophication Survey was included.
Key indicators sampled for the Survey of the Nation's Lakes included the following:
• Trophic indicators, such as in situ temperature and dissolved oxygen profiles, water
chemical quality, nutrient concentrations, chlorophyll a levels, transparency measured
by Secchi disk, turbidity, and color
• Ecological integrity indicators, such as sediment diatom abundance, diversity, and
trends; phytoplankton abundance and diversity; zooplankton abundance and diversity;
shoreline physical habitat conditions; and benthic macroinvertebrate abundance and
diversity
Figure 13. Sampling locations for the survey
of the nation's lakes.
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National Water Quality Inventory: 2004 Report to Congress
• Recreational indicators, such as pathogen (Enterococci) concentrations, algal toxin
(microcystins) levels, and sediment mercury concentrations.
Analysis of the survey's data is underway in 2008, and a report on the condition of the
nation's lakes is planned for 2009.
National Rivers and Streams Assessment
Base Sites
National Rivers and Streams Assessment
EPA is undertaking a survey of the nation's rivers—including the "Great Rivers" of the
United States—and intends to combine it with a second Wadeable Streams Assessment.
In 2008 and 2009, field crews expect to collect data on indicators of the following:
• Ecological condition, such as the abundance and diversity of periphyton,
phytoplankton, benthic macroinvertebrates, and fish
• Recreational value, such, as fecal contaminant concentrations in water and
contaminant residue in fish tissue
• Physical habitat condition, such as bank stability, channel alterations, and invasive
species
• Water quality, such as
basic water chemistry.
The focus will be on
wadeable streams in the first year
of monitoring and non-wadeable
systems (e.g., rivers) in the
second. Figure 14 shows the
locations of the 1,350 new sites
that will be sampled and the 450
sites from the 2006 Wadeable
Streams Assessment will be re-
sampled for this survey. A
national report on rivers and
streams is scheduled for 2011.
For more information on the
National River and Streams
Assessment, visit
http://www.epa.gov/owow/riverss
urvey/index. html.
Projection: USAContis-jDusAlbersCqua'AreaConic USCSvefsion
Figure 14. Sampling locations for the
national rivers and streams assessment.
National Wetland Condition Assessment
In 2011, EPA and the states plan to conduct a survey (National Wetlands Condition
Assessment) of the condition of the nation's wetlands, with a report planned for 2013. EPA and
the states are working with the FWS to design the wetland assessment to ensure that it effectively
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National Water Quality Inventory: 2004 Report to Congress
complements the FWS Status and Trends reports, which focus on the distribution of wetlands
rather than their condition.
EPA is currently in the research phase of the National Wetland Condition Assessment
and has identified several significant challenges to designing and implementing a wetland
assessment on a national scale. These include designing the best sample frame and methods to
support a national report; selecting efficient, scientifically valid indicators; ensuring that
adequate resources are available; maintaining the resultant data; and building partnerships to
most effectively use the information gleaned from the National Wetlands Condition Assessment.
EPA is coordinating a number of regional pilot projects with states, academics, and other
federal agencies to test design approaches, field protocols, and indicators. EPA anticipates that in
2009, the project team will be making initial decisions on condition indicators and assessment
methods that can apply across the nation's wide range of wetland types. For more information on
the National Wetland Condition Assessment, visit http://www.epa.gov/owow/wetlands/survey.
Through the institution of regular probability surveys of all waterbody types, EPA and its partners in the
states and other federal agencies expect to be able to cost-effectively assess 100% of the water
resources of the United States and track trends in water quality overtime. This scientifically based
data will assist in the evaluation of the effectiveness of pollution-control activities and will greatly
improve our ability to manage the nation's water resources.
State-Scale Statistical Surveys
More than half of the states have begun to implement state-scale statistical or
probabilistic surveys to characterize the full population of a water resource type (e.g., streams,
lakes). The majority of these surveys are of streams and rivers, although lakes, coastal waters,
and wetlands are also surveyed.
States use probabilistic monitoring designs to develop estimates of water quality across
the entire state, based on a representative sample, and to examine trends in water quality over
time statewide. Probability surveys can eliminate the risk of generating a biased picture of water
quality conditions; they provide information on changes in water quality over time statewide, and
serve as a cost-effective benchmark of the effectiveness of the state's water quality program.
Also as part of the probability assessment, a state can produce an estimate of the accuracy of its
assessment results. The results also provide information on whether it would be useful to target
certain waters for further assessment, or if limited resources for water quality assessment can be
used more effectively in other ways.
States use targeted monitoring, on the other hand, to meet state management objectives
such as identifying specific waters that are not meeting water quality standards, setting priorities
for impaired waters, and tracking the restoration of individual waters. The two approaches are
not expected to provide the same results because they are designed to achieve different
objectives.
Comparing the results of the two monitoring designs is a useful evaluation tool for the
state. For example, the statistical survey's overall description of the full population of waters
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National Water Quality Inventory: 2004 Report to Congress
provides a useful benchmark for comparing the results of targeted monitoring activities and can
help the state identify potential gaps in its targeted monitoring program.
The following are examples of how some states use probability assessments for water
quality assessment reporting in 2004. It is important to note that for the 2004 reporting cycle,
statewide probability assessments are still a fairly new development, and most states are only
beginning to report their findings.
South Carolina
South Carolina's monitoring program includes a probability-based component to
complement its targeted monitoring activities. Probability-based monitoring is conducted for
streams, lakes/reservoirs, and estuaries. Each year, a new statewide set of probability-based
random sites is selected for each waterbody type. These random sites are sampled on a monthly
basis for one year. South Carolina's 2004 Integrated Report (South Carolina DHEC, 2004)
includes details on site selection.
South Carolina provides tables comparing assessment results from its traditional
monitoring program and its probability-based assessment results for rivers and streams and for
estuaries, including a discussion of the findings.
For rivers and streams, the traditional approach included data from 630 monitoring
stations strategically located around the state, many of which include biological
(macroinvertebrate) and chemistry data. Approximately 15,300 stream miles—or about half the
state's total 29,794 stream miles—were assessed using the traditional 305(b) assessment
approach.
South Carolina summarized data from a total of 58 randomly located stream sites for the
probability-based assessment conclusions, 29 of which were sampled in 2001 and 29 of which
were sampled in 2002 (Table 6). These sites represent the total stream miles in the state,
weighted by stream size (i.e., based on the relative proportion of small headwater streams,
second order or intermediate streams, and larger streams to the stream resource as a whole).
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National Water Quality Inventory: 2004 Report to Congress
Table 6. Traditional vs. Probability-based Assessment Results for Rivers and Streams in
South Carolina (South Carolina DHEC, 2004)
Use Support
Category
Aquatic Life Use
Recreational Use
Degree of Use Support
Fully supporting
Partially supporting
Not supporting
Fully supporting
Partially supporting
Not supporting
Percent of assessed miles
in category — traditional
305(b) approach
65.3%
12.1%
22.5%
59.3%
21.5%
19.2%
Estimated percent of
total resource in
category — probability-
based approach
79.0%
5.9%
15.0%
49.9%
14.6%
35.5%
For its probability-based estuarine condition conclusions, the State summarized data from
60 randomly located estuary sites—30 sampled in 2001 and 30 sampled in 2002. These sites
represent the total estuarine area in the state. Probability-based approach results were compared
to the traditional approach, under which 221 square miles of South Carolina's total 401 square
miles of estuaries were assessed (Table 7).
Table 7. Traditional vs. Probability-based Assessment Results for Estuaries in South
Carolina (South Carolina DHEC, 2004)
Use Support
Catgory
Aquatic Life Use
Recreational Use
Degree of Use Support
Fully supporting
Partially supporting
Not supporting
Fully supporting
Partially supporting
Not supporting
Percent of assessed
square miles in category
- traditional 305(b)
approach
68.0%
14.4%
17.6%
94.1%
4.5%
1.4%
Estimated percent of
total resource in
category — probability-
based approach
75.3%
3.0%
21.7%
100%
~
~
Indiana
In Indiana, probability-based representative samples are used to determine overall aquatic
life use support, as part of the state's rotating basin approach (i.e., a plan for monitoring a subset
of the state's watersheds on a rotating 5-year cycle, such that in 5 years, all watersheds have been
cumulatively monitored). A stratified random sampling design is used to generate sampling sites
and provide a representative sample set for each basin. A fish community Index of Biotic
Integrity (IBI) is determined for each sampling location, and the results of each year's sample
data are analyzed to estimate the percentage of stream miles supporting aquatic life use for each
basin. This approach allows the state to make statistically valid estimates of aquatic life use
support for a large geographic area (e.g., a basin) with a relatively small number of
representative samples. For its 2004 Integrated Report (Indiana DEM, 2004), Indiana's
probability-based program found that 22,157 stream miles in the state's major river basins
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National Water Quality Inventory: 2004 Report to Congress
supported aquatic life and 13,168 miles did not support uses, for a total of 35,325 river and
stream miles covered by the probabilistic assessment.
Indiana's probability-based sampling design, known as the Watershed Monitoring
Program, allows the state to predict with reasonable certainty what percentage of its rivers and
streams are impaired. An individual stream or stream reach is considered assessed only when
sufficiently detailed monitoring data representative of that stream are available. According to the
state, the principal advantage of the probabilistic monitoring approach is that it allows the agency
to meet the goals of assessing all the waters of the state (in terms of the overall quality of each
basin) while providing data that can also be used to make waterbody-specific assessments.
Florida
Florida uses a three-tiered approach to monitor surface water quality, ranging from the
general to the specific. Tier 1, or probability monitoring, addresses statewide and regional
questions and is used to develop statistical estimates of statewide water quality based on a
representative sample. It allows the state to assess 100% of the waters of the state over a 5-year
period. Tier 2 addresses basin-specific and stream-specific questions (e.g., to verify waterbody
impairment), and Tier 3 addresses site-specific questions, such as those associated with permits
and the development of TMDLs.
The first cycle of the statewide probability assessment through the Integrated Water
Resource Monitoring Network began in 2000 and was completed in 2003. The results for each
basin are aggregated by waterbody type and assessed against water quality targets to assess the
overall health of that type of water in the basin. Florida assessed rivers and streams, large lakes,
and small lakes using this approach (see Figure 15).
Chlorophyll-*
(ChW)
Meeting Threshold
I'.irti.illv Meeting Threshold
Not Meeting Threshold
Dissolved Oxygen
(DO)
• Meeting Threshold
• Partially Meeting Threshold
• Not Meeting Threshold
Dissolved Oxygen
(DO)
Figure 15. Summary of statewide condition for Florida rivers and streams (left)
and large lakes (right) (Florida DEP, 2004).
Although the report (Florida DEP, 2004) presents preliminary results for the statewide
probability assessment, it also notes the fundamental differences between this approach and the
basin and stream assessments of Tier 2. Assessment targets, parameters monitored, and sample
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National Water Quality Inventory: 2004 Report to Congress
sizes are different between the two types of assessments. The results of the probability network
should be more representative of statewide conditions and may be able to shed light on any
biases in the basin and stream assessments due to, for example, the location of monitoring
stations. The State plans to make comparisons between both types of monitoring approaches as
its probability network continues to evolve.
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National Water Quality Inventory: 2004 Report to Congress
IV. Future Reporting
In March 2003, EPA issued guidance describing the basic elements of a state monitoring
and assessment program. In response to this guidance, states have prepared long-term strategies
that address comprehensive monitoring of all water types, including those for which little data
currently exist. Along with the traditional, targeted monitoring approach, which describes the
condition of individual waters of concern, probability surveys are an important component of
comprehensive water monitoring programs, providing a cost-effective means of assessing and
reporting on status and trends in overall populations of waters (e.g., streams and rivers, lakes).
In the future, 305(b) reports will be able to provide statistically valid water quality data that is
comparable across states.
The states and EPA are taking steps toward streamlining and improving water quality
monitoring and assessment by integrating monitoring and reporting requirements under sections
305(b) and 303(d) of the Clean Water Act (see the section Background, Integrated Water Quality
Reporting of this report/ EPA has issued guidance to the states to clarify reporting requirements
for the 2008 reporting cycle and has established a goal that all 50 states and 6 territories and
jurisdictions use the integrated reporting format by 2008. EPA continues to promote this
comprehensive assessment approach to improve the states' ability to track both programmatic
and environmental goals of the Clean Water Act, and ideally, to increase the pace of achieving
these important environmental goals. (See http://www.epa.gov/owow/tmdl/ for more information
on EPA's national water quality reporting guidance.)
Electronic reporting of water quality information is a continuing EPA priority and
involves a significant commitment at the state and national levels. EPA and the states are
working to ensure that each assessed watershed and waterbody is identified using a consistent
national surface water locational system, the National Hydrography Dataset (see
http://nhd.usgs.gov/ for more information), and that electronic reporting continues to improve.
EPA intends to continually adapt and improve the ATTAINS database to reflect new reporting
requirements and the full range of state monitoring activities, including state-scale probability-
based surveys, and will continue to fully support state efforts to adopt electronic reporting. This
commitment to providing more comprehensive, easily shared water quality information will help
managers and the public make more informed decisions about the future of our waters.
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National Water Quality Inventory: 2004 Report to Congress
V. References
Florida DEP (Department of Environmental Protection). 2004. Integrated Water Quality
Assessment for Florida: 2004 305(b) Report and 303(d) List Update. Florida Department of
Environmental Protection, Division of Water Resource Management, Tallahassee, FL.
Indiana DEM (Department of Environmental Management). 2004. Indiana Integrated
Water Quality and Assessment Report. Indiana Department of Environmental Management,
Indianapolis, IN.
South Carolina DHEC (Department of Health and Environmental Control). 2004. The
State of South Carolina's 2004 Integrated Report. South Carolina Department of Health and
Environmental Control, Columbia, SC.
U.S. EPA (Environmental Protection Agency). 2006. Wadeable Streams Assessment.
EPA/841-B-06-002. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
U.S. EPA (Environmental Protection Agency). 2008. National Coastal Condition Report
III. EPA/842-R-08-002. U.S. Environmental Protection Agency, Office of Research and
Development and Office of Water, Washington, DC.
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