&EPA
United States
Environmental
Protection Agency
Office of Research
and Development
Washington, DC 20460
EPAA620/R-01/004b
October 2001
EMAP-West Communications
Developing Indicators of Condition for Surface Waters of the West
Under the Clean Water Act, the states and
tribal nations have responsibility for
measuring the extent to which their waters
support their designated uses, and for
determining the major causes if they are
impaired. To respond to this requirement
as well as to form the basis for an environ-
mental "report card", a nationally consis-
tent set of scientifically defensible indica-
tors is essential. EPA's national and
regional managers are also interested in
using indicators in the context of the
Government Performance Results Act
(GPRA), which requires the Agency to
determine if our environmental expenditures are in fact result-
ing in the environmental benefits or improvements expected.
With planning and coordination, the same suite of carefully
chosen environmental indicators can meet Clean Water Act,
GPRA, and "report card" goals. The Agency's Environmental
Monitoring and Assessment Program (EMAP) is making a
major contribution to the science of indicator development and
its practical application.
Ecological indicators provide measures of the condition of those
aspects of the environment we are trying to protect - human
health and ecological resources. For example, when we wish to
assess the biological condition (or Aquatic Life Use (ALU) in
Clean Water Act terminology) of our aquatic systems (streams,
rivers, lakes, and estuaries), the most direct measurements are
those made of the plants and animals themselves. The chemical
and physical properties of aquatic systems are important indica-
tors of the stresses on the systems, and are frequently used to
assess the causes of impaired condition.
EMAP has developed a set of criteria for choosing which
indicators are useful in a survey of condition of ecological
resources. These criteria include:
• Can we practically measure the indicator in a survey?
• Is it responsive to different environmental conditions -
natural and/or human caused?
• Is it repeatable - will repeated measurements at the same
site give the same answer?
• Can it be "ranked" relative to expectations?
When an indicator passes the above tests, it can successfully be
utilized in a regional or national monitoring program.
The Surface Waters component of EMAP-West (covering the
twelve conterminous states in EPA Regions 8, 9, and 10) has
developed a core set of indicators of ecological condition and
environmental stressors. These include:
• Biological assemblages (fish, macroinvertebrates, and algae)
• Ambient Water Chemistry (nutrients, acid/base status, etc.)
• Fish Tissue Contaminants (mercury, metals, PCB congeners,
persistent organics)
• Physical Habitat (sedimentation, in-stream and riparian
habitat structure, etc.)
• Watershed characteristics (landcover/landuse, road density,
population density, etc.)
Biological measures will form the primary basis for assessing
Aquatic Life Use support, with chemical, physical, and water-
shed measures being used to assess and rank the relative impor-
tance of specific stressors to ALU. The regional, state, and tribal
partners involved in the EMAP-West have all agreed to the core
indicators and will, for the first time, use common field and
laboratory protocols across the West. Because of this commonal-
ity, EMAP-West provides the ability to share environmental
indicator data across state and regional boundaries throughout
the West for both ambient and reference conditions and will
result in the first statistically defensible assessment of baseline
conditions for western streams.
For further information, contact:
John Stoddard
Surface Water Lead
Stoddard.John@epa.gov
(541 )754-4441
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