The National Water Quality Inventory: Report to
            Congress for the 2002 Reporting Cycle - A Profile


In 2002, states reported that about 45% of assessed stream miles, 47% of assessed lake acres,
and 32% of assessed bay and estuarine square miles were not clean enough to support uses such
as fishing and swimming.  About 30% of U.S. waters were assessed by the states for this report.
Leading causes of impairment in assessed waters include excess levels of nutrients, metals
(primarily mercury), sediment and organic enrichment.  Top sources of impairment include
agricultural activities, hydrologic modifications, atmospheric deposition, industry, and unknown
or unspecified sources.
The National Water Quality Inventory:
Report to Congress for the 2002
reporting cycle summarizes water
quality assessments submitted to the
U.S. Environmental Protection Agency
(EPA) by the states under Section 305(b)
of the Clean Water Act.

This report is designed as a companion
to electronically-submitted state water
quality information already publicly
available on EPA's National Assessment
Database website at
www.epa.gov/waters/305b/index.html.
In addition to viewing the national
summary and information by state at this
Web site, users can click down to the
individual waterbody level to find out
more about water quality conditions.
To assess water quality, states, tribes and
other jurisdictions compare their
monitoring results to the water quality
standards they have set for their waters.
Water quality standards consist of three
elements: the designated uses (such as
drinking, swimming, or fishing) assigned
to waters; criteria (such as chemical-
specific thresholds that should not be
exceeded) to protect those uses; and an
anti-degradation policy intended to keep
waters that  do meet standards from
deteriorating from their current
condition.

Tables 1-3 (below) summarize key
findings of the 2002 state water quality
assessment reports.
Table 1. Summary of the Quality of Assessed Rivers, Lakes, and Estuaries
Waterbody
Type
Rivers
(miles)
Lakes
(acres)
Estuaries
(sq. miles)
Total Size
3,692,830
40.6 million
87,369
Amount
Assessed
(% of
Total)
695,540
(19%)
14,831,882
(37%)
30,446
(35%)
Condition of Assessed Waters
Good (% of
Assessed)
358,035
(51%)
7,073,207
(48%)
19,916
(66%)
Good but
Threatened
(% of
Assessed)
27,750
(4%)
810,775
(5%)
694 (2%)
Impaired
(% of
Assessed)
309,755
(45%)
6,947,901
(47%)
9,836 (32%)
Note: Percentages may not add up to 100% due to rounding.

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Table 2. Leading Causes of Impairment in Assessed Rivers, Lakes, and Estuaries
Rivers and Streams
Sediments/siltation
Pathogens
Habitat alterations
Lakes, Ponds and
Reservoirs
Nutrients
Metals
Organic enrichment
Estuaries
Metals
Nutrients
Organic enrichment
Table 3. Leading Sources of Impairment in Assessed Rivers, Lakes and Estuaries
Rivers and Streams
Agriculture
Unknown/unspecified*
Hydrologic modifications
Lakes, Ponds and
Reservoirs
Unknown/unspecified*
Agriculture
Atmospheric deposition
Estuaries
Unknown/unspecified*
Industrial discharges
Municipal discharges
 Source unknown or undocumented due to insufficient information. In previous national 305(b) reports, EPA did not
include this category in summary statistics.
The information summarized for the
2002 cycle should not be compared to
past reports, for a variety of reasons.
This report summarizes information
reported by states for only a portion of
their waters (e.g., 19% of total river and
stream miles); the portion of waters
assessed may vary from cycle to cycle.
Data were collected by states to meet
specific needs, using a variety of
sampling methods and parameters, water
quality standards, and time periods.  The
information in this report is most useful
for summarizing the nature of water
quality problems in assessed state
waters, identifying those waters not
meeting water quality standards, and
helping states  set priorities for
restoration.

EPA is continuing to work with states to
improve the quality of this Report to
Congress in response to the Government
Accountability Office and other
independent organizations. One key
effort is building state capacity to
implement probability surveys of state
waters in a nationally consistent manner.
Probability surveys are a statistical
approach for selecting unbiased
monitoring sites that represent the
population of a water resource. This is a
cost effective design for reporting on the
condition of all waters, tracking whether
waters are getting better or worse
statewide, and identifying key stressors
that are both widespread and pose a
significant risk to water quality. EPA
views these  state surveys as a critical
complement to, not a replacement for,
the more traditional monitoring approach
represented  in this report.

The National Coastal Condition Reports and
the Wadeable Streams Assessment are two
such nationally consistent statistical surveys.
EPA and its state and tribal partners are also
planning statistical surveys of the nation's
lakes, rivers, and wetlands. For more
information on statistical surveys, visit
www. cpa. go v/o wo w/monitoring/rcporting .html.
 For a copy of the National Water Quality Inventory:
 Report to Congress, 2002 Reporting Cycle (EPA 841-R-
 07-001) go to www,CBa,g,QV/3Q5b or call 1-800-490-9198.
       USEPA Office of Water
        EPA 841-F-07-003
          October 2007

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