\
              The National Water Quality Inventory: Report to Congress
                         for the 2004 Reporting Cycle - A Profile
              In 2004, states reported that about 44% of assessed stream miles, 64% of assessed lake
              acres, and 30% of assessed bay and estuarine square miles were not clean enough to
              support uses such as fishing and swimming. Less than 30% of U.S. waters were assessed
              by the states for this report. Leading causes of impairment included pathogens,
              mercury, nutrients, and organic enrichment/low dissolved oxygen.  Top sources of
              impairment included atmospheric deposition, agriculture, hydrologic
              modifications, and unknown or unspecified sources.
        The National Water Quality Inventory:
        Report to Congress for the 2004
        reporting cycle summarizes water
        quality assessments submitted to the
        U.S. Environmental Protection Agency
        (EPA) by 47 states and territories 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 ATTAINS website
        at www.epa.gov/waters/ir. 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 2004 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
3,533,205
41.7 million
87,791
Amount
Assessed
(% of
Total)
563,955
(16%)
16,230,384
(39%)
25,399
(29%)
Condition of Assessed Waters
Good (% of
Assessed)
302,255
(53%)
5,619,221
(35%)
17,721
(70%)
Good but
Threatened
(% of
Assessed)
15,698
(3%)
159,761
d%)
37
(<1%)
Impaired
(% of
Assessed)
246,002
(44%)
10,451,402
(64%)
7,641
(30%)
        Note: Percentages may not add up to 100% due to rounding.

-------
Table 2. Leading Causes of Impairment in Assessed Rivers, Lakes, and Estuaries
Rivers and Streams
Pathogens
Habitat alterations
Organic enrichment
Lakes, Ponds and
Reservoirs
Mercury
PCBs
Nutrients
Estuaries
Pathogens
Organic enrichment
Mercury
Table 3. Leading Sources of Impairment in Assessed Rivers, Lakes and Estuaries
Rivers and Streams
Agriculture
Hydromodification
Unknown/unspecified*
Lakes, Ponds and
Reservoirs
Atmospheric deposition
Unknown/unspecified*
Agriculture
Estuaries
Atmospheric deposition
Unknown/unspecified*
Municipal discharges
 Source unknown or undocumented due to insufficient information.
The information summarized for the
2004 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., 16% 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 probability-based
surveys. EPA and its state and tribal partners
are also conducting surveys  of the nation's
lakes, rivers, and wetlands. For more
information visit:
http://www.epa.aov/owow/monitorinq/nationalsurvevs.html.
 For a copy of the National Water Quality Inventory:
 Report to Congress, 2004 Reporting Cycle (EPA 841-R-
 08-00) go to www.epa.gov/305b or call 1-800-490-9198.
       USEPA Office of Water
        EPA 841-F-08-003
          January 2009

-------