United States     Office of Research and Development
            Environmental     Office of Water
            Protection Agency   Washington, DC 20460
EPA841-B-06-002
December 2006
www.epa.gov/owow/streamsurvey
4>EPA    Wadeable Streams Assessment

            A Collaborative Survey of the Nation's Streams




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 Mwfl


Front cover photo courtesy of the Colorado Division of Wildlife
Inside cover photo courtesy of Michael L. Smith, U.S. Fish and Wildlife Service

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Acknowledgments
   This report resulted Ironi a ground-breaking collaboration on stream monitoring. States came together
with the U.S. Km ironmental Protection Agency (1',1'A)  to demonstrate a cost-effective approach for
answering one ol (he nation's most basic water quality questions: What is the condition of our nation's
streams?

    The 1',1'A Office of Water would like to thank the many participants who contributed to this important
effort and  the scientists within the KI'A Olfice of Research and Development for then research and
refinement of the survey design,  field protocols, and indicator development. I hrough the collaborative
efforts of state environmental and natural  resource agencies, federal agencies, universities, and other
organizations, more than 150 field biologists were (rained to collect environmental samples using a
  O                                    O                                             I        O
standardized method, and more  than 25 taxonomists identified as many as 5()() organisms m each sample.
Each participating organization attended a national meeting to discuss and  formulate the data analysis
approach,  as well as regional meetings to evaluate and refine the results presented in this report.
 Collaborators
 .Alaska Department (it Environmental Conservation
 An/ona ( Kline and I ish Department
 .Arkansas Department of Environmental Quality
 California Department of Eish and Came
 California State Water Resources Control Hoard
 Colorado Department ol  Public Health .nul
  Em ironment
 Colorado Division of Wildlife
 Connecticut Department of Environmental Protection
 Delaware Department of  Natural  Resources
  and Environmental Control
 (ieorgia Departmeni of Natural Resources
 Idaho Department ol Em ironmental Quality
 Illinois hnvironmental Protection Agency
 Iowa Department ol Natural Resources
 Kansas Department ol Health and I'.nvironment
 Kentucky Division ol Water
 Louisiana Department of  Ian ironmental Quality
 Maine Departmeni ol Km ironmental Protection
 Maryland Department ol  Natural Resources
 Michigan Department of  Environmental Quality
 Minnesota Pollution Control Agency
Mississippi Department of Environmental Quality
Missouri Department of Conservation
Montana Department of Environmental Quality
Nevada Division of Environmental Protection
New Hampshire Department of Environmental
  Services
New Jersey Department of Environmental Protection
New Mexico Environment Departmeni
New York State Depanmem  of Environmental
  ('onscrvation
North Carolina Division of Water Quality
North Dakota  Department of Health
Ohio Environmental Protection Agency
Oklahoma ( 'onsei \.ttion Commission
Oklahoma Water Resources Hoard
Oregon Depanmem ol Environmental  Quality
Pennsylvania Department ol  Environmental Protection
South Carolina Department ol  Health
  and Environmental ( .ontrol
South Dakota Department ol Environment
  and Natural Resources
South Dakota Came, Eish and Parks
Tennessee Department ol  Environment and
  Conservation
fexas Commission of Environmental Quality
                                     TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Utah Division of Water Quality
Vermont Department of Environmental Conservation
Virginia Department of Environmental Quality
Washington State Department of Ecology
West Virginia Department of Environmental
  Protection
Wisconsin Department of Natural Resources
Wyoming Department of Environmental Quality
Eort Peck Assiniboine and Sioux Tribes
Guam Environmental Protection Agency
U.S. Geological Survey
U.S. EPA, Office of Environmental Information
U.S. EPA, Office of Water
U.S. EPA, Office of Research and Development
U.S. EPA, Regions 1-10
Center for Applied Bioassessment and Biocriteria
Central Plains ('enter for Bioassessmenr
New England Interstate Water Pollution Control
  Commission
The Council ol State Governments
Great Eakes Environmental Center
letra  lech, Inc.
EcoAnalysrs
University of Arkansas
Mississippi State University
Oregon State University
Utah State University
   The data analysis team painstakingly reviewed the data set to ensure its quality and performed the data
analysis. This team included Phil Kaufmunn, Phil Larsen, Tony Olscn, Steve Paulson, Dave Peck, John
Stoddard, John Van Sickle, and Lester Yuan from the KPA Office of Research and Development; Alan
Herlihy from Oregon State University; ("buck Hawkins from Utah State University; Daren Carlisle from
the U.S. Geological Survey; and Michael Barbour, Jcroen Cerritson,  Krik Lepow, Kristen Pavlik, and Sam
Stribhng from letra lech, Inc.

   The report was written by Steve Paulsen and John Stoddard from  the KPA Office of Research and
Development and Susan I loldsworth, Alice Mayio, and Ellen Tarquinio from  the KPA Office of Water.
Major contributions to the report were made by John Van Sickle, Dave Peck, Phil Kaufman n, and Tony
Olsen from the EPA Office of Research and Development and Peter Grevatt and Evan Hornig from KPA
Office of Water, Alan Herlihy from Oregon State University, Chuck  1 lawkins  from Utah State University,
and Bill Arnold from the Great Lakes Environmental ("enter. Technical editing and document production
support was provided by RTI International. This report was significantly improved  by the external peer
review conducted by Dr. Stanley V. Gregory, Kcologist, Oregon State University; Dr. Kenneth Reckhow,
Environmental Engineer, Duke  University; Dr. Kent Thornton, Principal Ideologist, K'I'N Associates; Dr.
Scott Urquhart, Statistician, Colorado State University; and Terry M. Short of the U.S. Geological Survey.
The Quality Assurance Officer for this project was Otto  Gutcnson from the KPA Office of Water.
TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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 Table of Contents
Acknowledgments	i i
   Collaborators	iii
Executive Summary	KS-2
Introduction	2
Chapter 1 - Design of the Wadeable Streams Assessment	6
   Why focus on wadeable streams?	6
   What area docs the WSA cover?	9
   What areas are used to report WSA results?	13
   1 low were sam pi i ng sites chosen ?	15
   11 ow were wate rs assessed ?	19
   Setting expectations	23
Chapter 2 - Condition of the Nation's Streams	26
   Background	26
   Indicators of Biological Condition	26
     Macroinvertebrate Index ol Biotic Condition	28
     Macroinvertebrate Observed/Expected (O/E) Ratio ofTaxa Loss	31
   Aquatic Indicators of Stress	33
     Chemical Stressors	33
     Physical Habitat Strcssors	39
     Biological St ressors	45
   Ranking of Strcssors	46
     Ext en t o f St ressors	46
     Relative Risk of Strcssors to Biological Condition	48
     Combining MX tent and Relative Risk 	50
Chapter 3 — Wadeable Streams Assessment Ecoregion Results	52
   Northern Appalachians Hcoregion	54
     Physical Setting	54
     Biological Setting	54
     Human Influence	54
     Su m maty of WSA Find i ngs	55
   Southern Appalachians Hcoregion	58
     P h y s i c a 1 S e 11 i n g	58
     Biological Setting	58
     Hu man I n flucncc	59
     Su m mary of WSA Find i ngs	59
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  Coastal Plains Kcoregion	61
     Physical Setting	61
     Biological Setting	62
     Human InHuence	62
     Summary of WSA Findings	63
  Upper Midwest Hcoregion	65
     Physical Setting	,	65
     Biological Setting	65
          O         O
     Human In Hue i ice	65
     Summary of WSA Findings	66
  Temperate Plains Fco region	68
     Physical Setting	68
     Biological Setting	68
     I lunian InHuence	68
     Summary of WSA Findings	69
  Southern Plains Kcoregion	71
     Phys i cal Se ft i n g	71
     Biological Setting	7'1
     I 1 uman Influence	72
     Summary of WSA Findings	7'2
  Northern Plains F.coregion	,	74
     Physical Setting	74
     Biological Setting	74
     Human Influence	75
     Summary of WSA Findings	75
  Western  Mountains Lcoregion	 	77
                          O
     Physical Setting	77
     Biological Setting	78
     I luman Influence	78
     Summary of WSA Findings	78
  Xeric Ecoregion	81
     Physical Setting	81
     Biological Setting	8 1
     Human Influence	8 1
     Summary of WSA Findings	81
             j               O
TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter 4 — Summary and Next Steps	86
   Su m mary	86
   Ncxr Steps	88
Glossary of Terms	91
Sources and References	93
   (ieneral  Rcrerences	93
   Si ream and  River Sam pi ins; and Laboratory Methods	94
   Probability  Designs	95
   Ideological Regions	95
   Indices of Biouc Integrity	96
   Observed/1,xpeaed Models	96
   Physical  Habitat	96
   Reference Condition	97
   Other KMAP Assessments	97
   Biological Condition Gradient/Quality of Reference Sites	97
   Relative  Risk	97
   Nutrients	98
                                   TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Figures
  \      Stnihler stream order diagram	7
  2      Stream characteristics change as the stream's si/.c or stream order increases	8
  3      Major rivers and streams of the conterminous United States	9
  4      Average annual precipitation of the United States, 1961-1990	10
  5      Major land cover patterns of the conterminous United States	1 1
  6      Human population density (people per square mile)  based on the
          2000 U.S. Census Bureau data	12
  7      Three major regions were surveyed for the WSA	13
  8      Nine ecoregions were surveyed for the WSA	14
  9      Length ofwadeable, perennial  streams in each WSA  ecoregion	 16
 10      Sites sampled for the WSA by EPA Region	 17
 1 1      Reach layout for sampling	 19
 12      Stream macroinvertebrates	20
 13      Biological condition of streams based on Macroinvertebrate Index of Biotic Condition	30
 14      Macroinvertebrate taxa loss as measured by the O/E  Ratio of Taxa Loss	32
 1 5      Total phosphorus concentrations in U.S. streams	35
 16      Total nitrogen concentrations in U.S. streams	36
 17      Salinity conditions  in U.S. streams	37
 1 8      Acidification in U.S. streams	39
 19      Streambed sediments in U.S. streams	41
 20      In-stream fish habitat in U.S. streams	42
 21      Riparian vegetative cover in U.S. streams	43
 22      Riparian disturbance in U.S. streams	45
 23      Extent of stressors	47
 24      Extent of stressors and their relative risk to Macroinvertebrate Condition
          and O/K Taxa Loss	49
 25      Ecoregions surveyed for the WSA	53
 26      WSA survey results for the Northern Appalachians ecoregion	56
 27      WSA survey results for the Southern Appalachians ecoregion	60
 28      WSA survey results for the Coastal Plains ecoregion	63
 29      WSA survey results for the Upper Midwest ecoregion	67
 30      WSA survey results for the Temperate Plains ecoregion	70
 31      WSA survey results for the Southern Plains ecoregion	72
 32      WSA survey results for the Northern Plains ecoregion	75
 33      WSA survey results for the Western Mountains ecoregion	79
 34      WSA survey results for the Xeric ecoregion	83
The Wodeob/e Streams Assessment: A Collaborative Survey of the Nation's Streams

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Acronym  List
"F
ANC
KM Ps
CAAA
CWA
EMAP
KPA
I;WS
km
mi
NAPAP
NC:A
NC;CR
NCCRII
NEP
NKP CC:R
NHI)
NLCD
NOAA
o/E
l>CBs
RBS
TDS
(ieq/I.
USCS
VOCs
WSA
decrees Fahrenheit
acid ncutrah/ing capacity
best management practices
Clean Air Act Amendments
dean Water Act
Environmental Monitoring and Assessment Program
U.S. Environmental Protection Agency
U.S. Fish and Wildlife Service
kilometers
square miles
National Acid Precipitation Program
National Coastal Assessment
National Coastal Condition Report
National Coastal Condition Report II
National Kstuary Program
National Estuary Program Coastal Condition Report
National Hydrography Dataset
National Eand ('over Dataset
National Atmospheric and Oceanic Administration
observed/expected
polychlorinared  biphenyls
relative bed stability
total dissolved solids
microequivalcnts per liter
U.S. Ceological  Survey
volatile organic compounds
Wadeable Streams Assessment
                                  The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Executive Summary
               #*.-*

  'V\ .-v A ' . X.:-^
                          2
                          §.
                          o
                          Z

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Executive Summary
Executive Summary

   "I started out thinking of America as
highways and state lines. As I got to know it
better, I began to think of it as rivers. America
is a great story, and there is a river on every
page of it. "

   This quote by well-known journalist Charles
Kuralt reflects on the central role that rivers and
streams have played in shaping the history and
character of our nation. Because the health and
survival of U.S.  families and communities arc-
dependent on these waterboclies, their condition,
as well as how they arc protected,  reflects our
values and choices as a society.

   The Wadeable Streams Assessment (WSA)
provides the first statistically defensible summary
of the condition of the nation's streams and small
rivers. In the 35 years since the passage of the
Clean Water Act (CWA), the U.S. Congress,
American public, and oilier interested parties have
asked the U.S. Environmental Protection Agency
(EPA) to describe the water quality condition of
U.S. waterbociics. These  requests have included
seemingly simple questions:  Is there a water
quality  problem? How extensive is the problem?
Does the problem occur  in "hotspots" or is it
widespread? Which environmental stressors affect
the quality of the nation's streams and rivers, and
which are most  likely to  be detrimental? This
WSA report presents the initial results of what
will be a long-term partnership between EPA,
other federal agencies, states, and tribes to answer
these questions.
  Little Washita River, OK, in the Southern
  Plains ecoregion (Photo courtesy of Monty Porter).
   The WSA encompasses the wadeable streams
and rivers that account for a vast majority of the
length of flowing waters in the United States. To
perform the assessment, EPA, states, and tribes
collected chemical, physical, and biological data
at  1,392 wadeable, perennial stream locations to
determine the biological condition of these waters
and the primary stressors affecting their qiulity.
Research teams collected samples at sites chosen
using a statistical design to ensure representative
results. The results of this analysis provide a clear
assessment of the biological quality of wadeable,
perennial streams and rivers across the country,
as  well as within each of three major climatic and
landform regions and nine ecological regions, or
ecoregions.
 The Wadeable Streams Assessment A Collaborative Survey of the Nation's Streams

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                                                  Executive Summary
   1 he information provided in this report fills an
important  gap in  meeting the requirements of the
CWA. The purpose of the WSA is four-fold:

 • Report  on the ecological (biological, chemical,
   and physical) condition of all wadeable, peren-
   nial streams and rivers within the conterminous
   United  States. (Pilot assessment projects arc-
   also underway  in Alaska and I lawan.)
 • Describe  the biological condition of these
   systems using direct measures of aquatic life.
   Assessments  of stream quality have historically
   relied primarily on chemical analyses of water,
   or sometimes, on the status ot game fish.
 • Identify and rank the relative importance ol
   chemical  and physical stressors  (disturbances)
   alfecting stream and river condition.
                               , 1.7%
                                                    •  Enhance the capacity of states and tribes to
                                                      include these design and measurement tools
                                                      in their water quality monitoring programs
                                                      so that assessments will be ecologically and
                                                      statistically comparable, both regionally and
                                                      nationally.
                                                      The results of the WSA show that 42% of  the
                                                   nation's stream  length is in poor biological
                                                   condition compared to least-disturbed reference
                                                   sites in the nine ecoregions, 25% is in fail-
                                                   biological condition, and  18% is in good biolog-
                                                   ical condition (Figure ES-1). five percent of the
                                                   nations stream  length was not assessed for
                                                   biological condition during the WSA.
                                                       2.0%
                                                                           9.5%
                             West
                          152,425 miles
                                                      Plains and Lowlands
                                                        242,264 miles
Eastern Highlands
  276,362 miles
     National
Biological Condition
      5.0%
      I  Good
      D  Fair
      ED  Poor
      D  Not Assessed
                                   WSA
                               Major Regions*
                              CD West
                              CZ] Plains and Lowlands
                              ESI Eastern Highlands
Figure ES-I. Biological condition of wadeable streams (U.S. EPA/WSA).
                               TheWadeable Streams Assessment A Collaborative Survey of the Nation's Streams

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Executive Summary
   Of the three major regions discussed in
this report, the West is in the best biological
condition, with 45% of stream length in good
biological condition. The Plains and Lowlands
region has almost 30% of stream length in good
biological condition and 40% in poor biological
condition. The Kastcrn  Highlands region  presents
the most concerns,  with  only 18% of stream
length in good biological condition and 52% in
poor biological condition.

   The WSA also examines the key factors most
likely responsible for diminishing biological
quality in flowing waters, as determined by
aquatic macroinvertcbratc communities. I he
most widespread stressors observed across [he
country and in each of the three major regions
are nitrogen, phosphorus, riparian disturbance,
and streambed sediments. Increases in nutrients
(e.g., nitrogen and phosphorus) and streambed
sediments have the  highest impact on biological
condition; the risk of having poor biological
condition was two times sireatcr for streams
                     scoring poor tor nutrients or streambed sediments
                     than for streams that scored in the good range for
                     die same stressors (Figure ES-2).

                       Understanding the current condition of the
                                    O
                     nation's wadeitble streams and rivers is critical
                     to supporting the development of water quality
                     management plans and priorities that help
                     maintain and restore the  ecological condition of
                     these resources. This report provides a primary-
                     baseline assessment to track water quality  status
                     and trends. 1 lie results of the WSA and similar
                     assessments in  the luttire will  inform the public,
                     water quality managers, and elected officials of the
                     effectiveness of efforts to protect and restore water
                     quality, as  well as  the potential need to refocus
                     these efforts.

                       Readers who wish to learn  more about  the
                     technical background of the WSA are directed
                     to literature cited in the References section at
                     the end of this report and to material posted on
                     the  LPA Web site at htlp://www.epa.go\7owow/
                     streamsurvev.
             Nitrogen
           Phosphorus
    Riparian Disturbance
   Streambed Sediments
   In-stream Fish Habitat
Riparian Vegetative Cover
               Salinity
           Acidification
                               Extent of Stressor
                                   Relative Risk to
                                 Biological Condition
                            10
20
30
40
                         Percentage Stream Length in Most
                               Disturbed Condition
2            3
 Relative Risk
  Figure ES-2.  Extent of stressors and their relative risk to the biological condition of the
  nation's streams (U.S. EPA/WSA).
The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Introduction

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Introduction
Introduction
   In 1972, the U.S. Congress enacted the
landmark Clean Water Act (CWA) to protect the
nation's vital water resources. A critical section
of the CWA calls for periodic accounting to
Congress and the American public on the success
or failure of efforts to protect and restore the
nation's waterbodies. In recent years, a number of
groups reviewed the available data and concluded
that the U.S. Environmental Protection  Apencv
                                      o
(EPA) and state environmental agencies  have been
unable to provide Congress and the public with
adequate information regarding the condition of
the nation's waterbodies.

   In 2000, the General Accounting Office issued
a report noting that KPA and the states could not
make statistically valid inferences about  water
quality and lacked  data to support  management
decisions. A National Research Council  report  in
2001 found that a  uniform, consistent approach
to ambient monitoring and data collection
was necessary to support core water programs.
In 2002, the National Academy of Public
Administration and the H. John Hem/, 111 Center
tor Science, Economics, and the Environment
issued similar conclusions.

   following the 2002 release of the Hein/
Center's report The State of the Nation's Ecosystems,
the national newspaper USAToday published
an editorial discussing the lack of environmental
information available to the public. This editorial
emphasized the failure of state and federal agencies
to fund  the collection of necessary environmental
data despite sxry effective collection of comparable
information on the U.S. economy, population,
energy usage, human health issues, and crime
rate. The editorial concluded that "without such
information, the public doesn't know when to
celebrate environmental successes,  tackle new
threats,  or end efforts that throw money down a
drain" (USAToday, September 21, 2002).
         Little Washita River, OK, in the Southern Plains ecoregion (Photo courtesy of Monty Porter).
 The Wadeable Streams Assessment: A Collaborative Survey of the Notion's Streams

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   To bridge this information gap, KPA, other
federal agencies, states, and tribes, are
collaborating to provide the public with improved
environmental information. This collaboration
includes a new monitoring effort to assess the
quality of the nation's  waterbodies, an effort that
has produced reports on three national water
quality assessments during (he past five years for
coastal and esttiarine waters (see Highlight:
National Report on  ("oitsltil Water*}. Similar efforts
are planned for other water resource assessments
in the future. The Wadeable Streams Assessment
(WSA)—the hrst nationally consistent,
statistically valid study of the nation's wadeable
streams—marks the continuation  of a
commitment to produce statistically valid
scientific assessments of the nation's fresh waters.
Introduction

   State water quality agencies, tribes, and other
partners, with support from KPA, conducted the
work for the WSA using standardized methods
at all sites to ensure the comparability o( results
across the country. Bevond yielding scientifically
                J    J      J      O           /
credible information on the condition and health
of the nation's wadeable streams, the WSA was
designed to provide states with funding and
expertise that enhances their ability to monitor
and  assess the quality of their waters.

   I1,PA and its collaborating partners plan to
conduct similar assessments of other types of
waterbodies (e.g., lakes, rivers, and wetlands) in
the future, with the goal of  producing updated
assessments for each type of waterbody every
five years. These repeated studies will ensure that
the public remains informed as to whether the
collective efforts to protect and restore the nation's
waters are meeting with success.
                                                                                                       -^ -7
                                                                                                       CL Z
                                    The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Introduction
      National Reports on Coastal Waters

        The National Coastal Assessment (NCA) surveys the condition of the nation's coastal resources,
      as well as state efforts to protect, manage, and restore coastal ecosystems. The results of these
      surveys are compiled periodically into the National Coastal Condition Report (NCCR) series. The
      states, EPA, and partner agencies, including the National Oceanic and Atmospheric Administration
      (NOAA), U.S. Geological Survey (USGS), and U.S. Fish and Wildlife Service (FWS), issued the National
      Coastal Condition Report II (NCCR II) in January 2005 as tr^e second in this series of reports on
      environmental surveys of U.S. coastal waters. The NCCR II includes evaluations of 100% of the
      nation's estuaries in the conterminous 48 states and Puerto Rico. Federal, state, and local agencies
      collected more than 50,000 samples between 1997 and 2000 for the NCCR II, using nationally
      consistent methods and a probability-based design to assess five key  indices of coastal water health:
      water quality, coastal habitat loss, sediment quality, benthic community condition, and  fish tissue
      contaminants levels.

        The National Estuary Program Coastal Condition Report (NEP CCR) focuses specifically on the
      condition of the 28 estuaries in the National Estuary Program (NEP) using data collected from  1997
      through 2003 for EPA's  NCA. The NEP  CCR also presents monitoring data collected and analyzed
      by each individual NEP and its partners for a variety of estuarine quality indicators. The 28 NEPs are
      using these data to develop and implement sets of program-specific indicators of estuarine condition.
 TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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  Chapter 1
Design of the Wadeable
Streams Assessment
   r
   y"

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Chapter I   Design of the Wadeable Streams Assessment

Design  of the
Wadeable  Streams
Assessment

Why  Focus on Wadeable
Streams?
   Like the network of blood vessels that supply
life-giving oxygen and nutrients to all parts
of the human body, streams and rivers form a
network that carries essential water  to all parts
of the nation. The human body has far more
small eapillaries than large, major arteries and
veins; similarly, only a few U.S. rivers span large
portions of the country (e.g., the Mississippi,
Missouri, or Columbia rivers). Most of the
nation's waterways are much smaller stream
and river systems that form an intimate linkage
between land and water.
   The WSA addresses these smaller systems,
which ecologists often refer to as "wadeable"
because they are small and shallow enough to
adequately sample without a boat. Almost every
slate, university, federal agency, and volunteer
group involved in water quality monitoring has
experience sampling these smaller flowing waters;
therefore, a wide range of expertise was available
for the WSA's nationwide monitoring effort.

  About 90% of perennial stream and river miles
in the United States arc small, wadeable streams.
Stream and river ecologists commonly use the
term Strahler stream order to refer to stream si/.e,
and wadeable streams generally fall into the 1st-
through  5th-order range  (Figure  1). Hirst-order
streams are the headwaters of a river, where-  the
life of a river begins; as streams join one another,
their stream order increases.  It is  important  to
note that many Ist-order streams, particularly
those located in the western  United States, do
not flow continuously. These intermittent or
ephemeral streams were not  included  in the WSA
because well-developed indicators to assess these
waterbodies do not yet exist. At the other end of
the  range are larger-order rivers and streams that
                Sawmill Creek, MA, in the Northern Appalachians ecoregion
                (Photo courtesy of Colin Hill,Tetra Tech, Inc.).
The Wodeob/e Streams Assessment: A Collaborative Survey of the Notion's Streams

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                                                      Chapter I    Design of the Wadeable Streams Assessment
             Figure  I. Strahler stream order diagram (U.S. EPA/WSA).  Stream size is
             categorized by Strahler stream order, demonstrated here for a watershed.
             The confluence (joining) of two Ist-order streams forms a 2nd-order stream;
             the confluence of two 2nd-order streams forms a 3rd-order stream.
are too deep for wadeable sampling methods.
 These deeper waterbodics will be included in a
future survey of non-wadeable rivers.

   Stream order (stream size) affects a stream's
natural characteristics, including the biological
communities that live in the stream, such as fish
and invertebrates. Very small Ist-order and 2nd-
order streams are often quite clear and  narrow
and are frequently shaded by grasses, shrubs, and
trees that grow along the stream bank (Figure 2).
 The food base of these streams is found along the
stream bank and tends to consist of leaves and
terrestrial insects, which dominate  the streams'
ecology, along with  algae that attach to rocks and
wood, aquatic insects  adapted to shredding leaves
and scraping algae, and small fish that feed on
these organisms. In contrast, larger 6th- and 7th-
order rivers typically appear muddy because their
flow carries accumulated sediments downstream.
These rivers are wide enough that the canopy
cover along their banks shades only a narrow
margin ol water along the river's edge. The food
base (or these waterboches shifts towards m-
stream sources, such as algae; downstream drift of
small organisms; and deposition of fine detritus.
Although the aquatic communities of larger rivers
include the algae and terrestrial insects found in
streams, these rivers are dominated by insects
adapted to filtering and gathering fine organic
particles, and larger fish that are omnivorous
(feeding on plants  and animals) and/or
piscivorous (feeding  on smaller fish).
                                    The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter /   Design of the Wodeob/e Streams Assessment
                                                                                         grazers
     -t
     2  -
                                                                                coarse
                                                                                particulate
                                                                                matter
fine
particulate
matter
                                                                          microbes   /sBp(
                                                               collectors    v~-£  -^    V.
                                                                          x< • Jf-    predators
                           Relative Channel Width


   Figure 2.  Stream characteristics change as the stream's size or stream order increases
   (Vannote et al., 1980).
The Wodeob/e Streams Assessment: A Collaborative Survey of the Nation's Streams

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What Area Does the WSA Cover?

   This WSA encompasses the wadeable streams
of the conterminous United States, or lower 4X
states (figure 3). This land area covers 3,007/iJ6
square miles (mi') and includes private, state,
tribal, and federal land. Although not  included
in this report, initial stream-sampling  projects
outside the conterminous United States have
begun ami will  be included in  future assessments.
for example, scientists in Alaska sampled streams
in the lanana River Basin (a subbasm  to the
Yukon River) during 2004 and 2005, and they
Chapter I   Design of the Wadeable Streams Assessment

 expect  to report their results m 2007; Citiam has
 begun implementation of a stream survey; and
 Puerto Rico is developing indicators for assessing
 the condition of its tropical streams. In addition,
 the State of Hawaii began stream sampling using
 WSA techniques on the island of Oahu in 2006.

    State boundaries offer few insights into the
 true nature of features that moid our streams and
 rivers. The most fundamental trait that defines
 U.S. waters is annual precipitation (figure 4).
 A sharp change occurs on either side of the
Figure 3. Major rivers and streams of the conterminous United States (NationalAtlas.gov, 2006).
Major rivers comprise only 10% of the length of U.S. flowing waters, whereas the nation's wadeable streams
and rivers comprise 90% of the length of U.S. flowing waters.
                                    The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter I    Design of the Wadeable Streams Assessment
100th longitude that runs from west Texas

through North Dakota, with precipitation falling

plentifully to the east, but sparsely to the west.

(The high mountains of the western United

States and the Pacific coast are exceptions to the

general scarcity of water in the  West.) The east-

west divide in moisture has not only shaped the

character  of the nation's waters, but also how they

are used, valued, and the even the legal systems

with which they are managed. A second divide

that defines the nature of U.S. rivers and streams

is the north-south gradient in temperature.
                                                      Young Womans Creek, PA, in the Southern
                                                      Appalachians ecoregion (Photo courtesy of the
                                                      Great Lakes Environmental  Center).
  Annual Average Precipitation
     (in inches) 1961-1990
    Ml  <5
        5-10
        10-15
        15-20
        20-25
        25-30
        30-35
    Wm  35-40
    *B  40-50
        50-60
60-70
70-80
80-100
100-120
120-140
140-180
180-200
Figure 4. Average annual precipitation of the United States, 1961-1990 (NOAA, National Climatic
Data Center). The 100th longitude meridian runs from Texas north through North Dakota and reveals a major
gradient of precipitation that defines differences in western and eastern streams.
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                                                       Chapter I    Design oftheWadeable Streams Assessment
   The nation includes a wide diversify of
landscapes, from the varied forests of the  Mast, to
the immense agricultural plains and grasslands
of the Midwest, to the deserts and shrublands
of the Southwest, to the giant mountain ranges
of the West (Figure 5).  In the eastern part of the
country, the Appalachian  mountains run  from
Maine to Alabama, crossing climatic boundaries
and separating the waters flowing to the Atlantic
Ocean from those flowing to the Gulf of  Mexico.
 The larger mountain ranges in the West link
their landscapes together: the Rockies through
the heart of the West; the Cascades, which
crown  the Northwest in snow; the Sierra Nevada
in California; and the Coastal Range, which
plummets to the Pacific Ocean, with a fault-block
shoreline that stretches from the Santa Monica
mountains to Kodiak Island. The Coastal Plains
of the Hast and Southeast and the Great Plains of
the interior provide other major landform features
that mark the country.
      H Forest
      I   I Agriculture
      ^f Wetland
      I   I Shrubland
      HH] Urban
      ^H Bare
      'based on NLCD 1992
Figure 5. Major land cover patterns of the conterminous United States (USGS, 2000).
                                    TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter I   Design of the Wadeable Streams Assessment

   The establishment and spread ol European
colonies and the Industrial Revolution intensified
the transformation of the nation's natural
landscape, as greater numbers of people arrived
and modified many of the features of the land and
waters. As the  nation's population grew and cities
and towns were established, tens of thousands
of dams were constructed to alter the flow of
virtually every major river in the United States.

   Historically, people have tended to  live where
water is more abundant. Current population
patterns based on 2000  U.S. Census Bureau
data reflect the historical abundance of waters
in the East and forecast the growing challenges
facing the water-scarce regions in the West, where
population has grown in recent years (Figure
6). 1 he current and future condition of the
nation's water.', will continue to be influenced
by population patterns, as well as how the
components of a watershed, including surface
water, groundwater, and the land itself, are used.
        Population
       Density 2000
   (people per square mile)
       1-4    ••  50-99
       5-9    Hi  100-249
       10-24  •  >2SO
Figure 6. Human population density (people per square mile) based on 2000 U.S. Census
Bureau data (ESRI, 2005).
T/ie Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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                                                     Chapter I   Design of the Wodeoble Streams Assessment
What Areas Are Used to Report
WSA Results?
   The conterminous United States is the
broadest-scale unit tor which WSA results are
reported. For this report, this area has been split
into three major regions—the Kastern Highlands,
the Plains and Lowlands, and the West. These
three regions correspond to major climate and
landform patterns across the United States
(Figure 7).
   The Eastern  Highlands region is composed
of the mountainous areas east or the Mississippi
River and includes the piedmont to the east
of the Appalachians and the interior plateau
to their west. The Plains and Lowlands region
encompasses the Atlantic and Gulf of Mexico
coastal plains and the lowlands of the Mississippi
Delta, as well as the portions of the Midwest from
the Dakotas down through most of Texas. The
West region includes the western portion of the
country, from the desert southwestern United
States and the Rocky Mountains to the Pacific
Ocean. Chapter 2 of this report describes the
WSA results tor these three major regions.
  V
    WSA Major Regions*
     fffi Eastern Highlands
     I  I Plains and Lowlands
     I  I West
    based on Omernik Level III ecoregions
Figure 7. Three major regions were surveyed for the WSA (U.S. EPA/WSA).
                                    TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter I    Design oftheWadeable Streams Assessment
   A finer-scale reporting unit included in
the WSA consists of nine ecological regions
(ecoregions) (Figure 8) that further divide the
three major regions. The three major regions
and the nine ecoregions outlined in this report
arc aggregations ot smaller ecoregions defined by
EPA. Areas are included  in an ecoregion based
on similar landform and climate characteristics.
For example, water resources within a particular
ecoregion have similar natural characteristics and
respond similarly to natural and anthropogenic
stressors. Typically,  management practices aimed
at preventing degradation or  restoring water
quality apply to many flowing waters with  similar
problems throughout an ecoregion. This report
presents results by ecoregions because the patterns
ol response to stress, and the stressors themselves,
are often best understood in a regional context.
The  results for the nine ecoregions are reviewed in
Chapter 3 of this report.

   I  he hastern Highlands region is divided into
two  ecoregions: the Northern Appalachians
ecoregion, which encompasses New  Kngland,
New York, and northern Pennsylvania, and the
Southern Appalachians ecoregion, which extends
from Pennsylvania into Alabama, through the
eastern portion of the Ohio Valley, and includes
the Oxark Mountains of Missouri, Arkansas, and
Oklahoma.
       WSA Ecological Regions*
  B| Northern Appalachians |   | Southern Plains
  I   I Southern Appalachians I   I Northern Plains
  HHH Coastal Plains      HI Western Mountains
  I   I Upper Midwest     I   I Xeric
  \   I Temporate Plains
Figure 8.  Nine ecoregions were surveyed for the WSA (U.S. EPA/WSA).
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                                                     Chapter I    Design of the Wadeable Streams Assessment
   The Plains and Lowlands region includes five
WSA ecoregions: the Coastal Plains, the Upper
Midwest, the Temperate Plains, the Northern
Plains, and the Southern Plains. The Coastal Plains
ecoregion covers the low-elevation areas of the Hast
and Southeast, including the Atlantic and Gulf
of Mexico coastal plains and the lowlands of the
Mississippi Delta, which extend from the Gulf of
Mexico northward through Memphis, TN. The
Upper Midwest ecoregion is dominated by  lakes
and has little elevation gradient. I he Temperate-
Plains ecoregion in the midwestcrn United  States
is probably most well-known as the Cornbelt. The
Northern Plains and Southern Plains ecoregions
are better known as the Great Prairies, with the
Northern Plains ecoregion encompassing North
Dakota, South Dakota, Montana, and northeast
Wyoming, and the Southern Plains ecoregion
encompassing parrs of Nebraska, Kansas, Colorado,
New Mexico, Oklahoma, and Texas.

   The West region includes two WSA ecoregions:
the Western Mountains ecoregion and the arid or
Xeric ecoregion. The Western Mountains ecoregion
includes the Cascade,  Sierra Nevada, and Pacific
Coast mountain ranges in the coastal states; the
Gila Mountains  in the southwestern states;  and the
Bittcroot and Rocky Mountains in the northern
and central mountain states.  The Xeric ecoregion
includes both the true deserts and the arid lands of
the Great Basin.

   Some states participating in the WSA assessed
an even finer state-scale resolution than the
ecoregion scale by sampling additional random sites
within their state borders. Although these data are
included in the analysis described in this report,
state-scale results are not presented for each state.
These states are preparing similar analyses that
reflect their respective water quality standards and
regulations.
How Were Sampling Sites
Chosen?
   The WSA sampling locations were selected
using modern survey design approaches. Sample
surveys  have been used in a variety of fields (e.g.,
election polls, monthly labor estimates, forest
inventory analyses, National Wetlands Inventory)
to determine the status of populations or
resources of interest using a representative sample
of a relatively few members or  sites. This approach
is especially cost effective if the population is so
large that all components cannot be sampled or
if obtaining a complete census of the resource is
unnecessary to reach the  desired level of precision
for describing conditions.
   Survey data are frequently reported in the
news. For example, the percentage of children
1-5 years old living in the United States who
have high lead levels in their blood is 2.2% +/-
1.2%, an estimate based on a random sample of
children in the United States. The WSA results
have similar rigor in their ability to estimate the
percentage of stream miles, within a range of
certainty, that arc in good condition.
   To pick a random sample, the location of
members of the population of  interest must
be known. The target population for the WSA
was the  wadeable, perennial streams in the
conterminous United States. The WSA design
team used the National Hydrography Dataset
(NHD)—a comprehensive set of digital spatial
data on  surface waters—to identify the location of
wadeable, perennial streams. They also obtained
information about stream order from the  River
Reach File, a  related series of hydrographic
databases that provide additional attributes about
stream reaches. Using these resources, researchers
determined the length of  wadeable streams for
each of the nine ecoregions (figure 9).
                                    The Wadeable Streams Assessment: A Col/aborative Survey of trie Nations Streams

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Chapter I    Design of the Wadeable Streams Assessment
    For tins WSA report, the wadeable stream miles
assessed for the nation, regions, and ecoregions are
referred to as the stream length.  1 he total stream
length represented in the WSA for the nation is
671,051  miles. For the Fastcrn Highlands, Plains
and Lowlands, and West regions, the  total stream
length assessed for the WSA  is 276, ">62 miles,
   —,                              .
242,264 miles, and 152/125 miles,  respectively.

    The \ ,3')2 sites sampled for the WSA were
identified using a particular type of random
sampling technique called a probability-based
sample design, m which every element in the
population has a  known probability of being
selected for sampling. This important feature
ensures that the results ol the WSA reflect the full
ran lie in character and variation amonir wadeable
   o                                o
streams across the United States. Rules for site
selection included weighting to provide balance
in the  number of stream sites from each of the
1st- through 5th-order si/.e classes and controlled
spatial distribution to ensure that sample sites were
distributed across the United States (Figure  10).
                             The WSA sites were allocated by KPA Region
                          and WSA ecoregion based on the distribution
                          of 1st- through "nil-order streams within chose
                          regions. Within each EPA Region, random sites
                          are more densely distributed where the perennial
                          1st- through Sth-order streams are more densely
                          located and more sparsely distributed where
                          streams are sparse. For example, EPA  Region 4
                          m the southeastern United States includes large
                          portions  ol the Southern Appalachian and (xusta
                          Plains ecoregions. The survey desien in  EPA
                                     O              .     D
                          Region 4 ideniified more sites in the Southern
                          Appalachians ecoregion, where the stream length
                          is  178,449 miles, than in the Coastal  Plains
                          ecoregion, where the stream length is  72,1.50
                          miles  (see Figure 9).

                             The basic sampling design drew 50 sampling
                          sites randomly distributed in each of the EPA
                          Regions and WSA ecoregions. Some ol the
                          unusually dense site patterns visible on Figure
                          10 occur because some states opted to increase
                          the intensity of random sampling throughout
                    National
                  (lower 48)
        Southern Appalachian
          Western Mountains
            Temperate Plains
       Northern Appalachians
               Coastal Plains
              Upper Midwest
                      Xeric
              Southern Plains
             Northern Plains
                                                      671,051
         ] 126,436
         100,879
        97,913
      72,130
j£] 36,547
g 25,989
119,263
^13,445
                            0            200,000         400,000         600,000         800,000
       Figure 9.  Length of wadeable, perennial streams in each WSA ecoregion (U.S. EPA/WSA).
The Wadeable Streams Assessment A Collaborative Survey of the Nation's Streams

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                                                       Chapter I   Design of the Wadeable Streams Assessment
Figure 10.  Sites sampled for the WSA by EPA Region (U.S. EPA/WSA).
their stare to characten/e statewide conditions.
Fifteen slates, including all states in hl'A
Regions 8, 9, and  10, increased the number of
random sites to 50 sites throughout each state
to support state-scale characteri/.attons of stream
condition. States also added clusters of random
sites to characteri/e areas of special interest in
Washington, Oregon, and California. When sites
from an area of intensification were used in the
ceo region assessments, the weights associated with
those sites were adjusted so that  the additional
sites did not dominate the results. The unbiased
site selection of the survey design ensures that
assessment results represent the condition of the
streams throughout the nation.
   An additional 1 50 reserve replacement sites
were generated for each of the  10 KI'A Regions.
These replacement sites were used when site
reconnaissance activities documented that one of
the original stream sites could not be sampled. For
example, sites were replaced when a waterbody
did not  meet the definition of a wadeable stream
(e.g., no flowing water over 50% of  the reach) or
was unsafe for sampling, or when access to the
stream was denied bv the landowner.
                                     TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter /    Design of" the Wadeable Streams Assessment
      WSA Sampling Frame

         The basis of the WSA target population is 1st- through 5th-order perennial streams, which are
      the streams most likely to be wadeable. The sampling frame used to represent the target population
      and to select the sites for the WSA is based on the perennial stream network contained in the
      USGS-EPA NHD.  The NHD is  a digitized version of I:IOOK USGS topographic maps and shows
      both perennial and non-perennial (e.g., intermittent and ephemeral) streams.

         The total stream length in the NHD stream and river network labeled perennial in the
      conterminous United States is  1,204,859 miles. Of this amount, 1,131,062 miles are  1st- through
      4th-order streams, which make up 91% of the total stream length of the nation's flowing waters (see
      figure below).

         Of the more than I million  miles of stream length labeled as perennial, almost 34% (400,000
      miles) were found to be non-perennial or non-target waterbodies (e.g., wetlands, reservoirs,
      irrigation canals).  The remaining target stream length represents the portion  of the NHD that
      meets criteria for inclusion in the WSA (e.g., perennial, wadeable streams). A portion of that target
      stream length was not sampled for various reasons, including denial of access by a landowner or
      inaccessibility.

         In addition to generating results on the  condition of perennial streams, the WSA provides data on
      the total length of perennial stream miles in the United States.  These results  will be  loaded into the
      NHD so that the database is updated on the status of perennial/non-perennial stream information.
              Total NHD Length

                I st - 4th Order

                    5th Order • 59,409 (S9t)

                    6th Order | 12,063(1%)

                    7th Order 1 31.850(3%)
                    8th Order
                              6,342 (< I %)
  1,240,849

31.062(91%)
                                                                             1,500,000
                            0       300.000     600,000      900jOOO      1200,000
                                                  Length (miles)
      Estimate of perennial length of streams and rivers from the NHD (U.S. EPA/WSA).
      The 1st- through 4th-order streams comprise 91% of total estimated stream length in the NHD.
      The 1st- through 5th-order streams form the basis for the sampling design frame for the WSA.
The Wadeable Streams/Assessment: A Collaborative Survey of the Nation's Streams

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                                                      Chapter I    Design of the Wadeable Streams Assessment
 How Were Waters Assessed?
   Each WSA site was sampled by a two- to four-
person field crew between 2000 and 2004 during
a summer index period. More than 40 trained
crews, comprised primarily of state environmental
staff, sampled 1,3')2 stream sites using
standardr/.ed field protocols,  f he held protocols
were designed to consistently collect data relevant
to the biological condition of stream resources
and the resources' kev stressors.
   During each sue visit, crews laid out the
sample reach and the numerous transects to
guide data collection  (Hgtire 1 1). held crews
sent water samples to a laboratory tor basic
chemical analysis, whereas biological samples
collected from 1 1 transects along each stream
reach were sent to taxonomists for identification
of macroinvertebrates. Crews also completed
roughly 35 pages of field forms,  recording data
and information about the physical characteristics
                                 Riparian Vegetation &
                                 Human Disturbance
                                                              Urge Wood
                                                             Tally (between
                                                              transects)
        Figure I I.  Reach layout for sampling (U.S. EPA/WSA).
                                    The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter I   Design of the Wodeob/e Streams Assessment
oi each stream and the riparian area adjacent to
its banks. Kach crew was audited, and 10% of the
sites were revisited as part  of the quality assurance
plan for the survey.

   'The use of standardized field and laboratory
protocols tor sampling is a key feature of the
WSA. Because ecologists use a range of methods
to sample streams, it is often difficult to compare
data collected by different states, regions,
or agencies on a regional or  national level.
Standardisation allows the data to be combined
to produce a nationally consistent assessment. In
addition to collecting a national set of consistent
data, this nationwide sampling effort provided
an opportunity to examine the comparability of
different sample protocols by applying both the
WSA method and various state or USGS methods
to a subset of ihe sites. A separate analysis is
underway to examine the comparability of
these methods and explore options for how the
resulting data may be used together.

   The WSA  uses benthic macroinvertebrates
(e.g., aqua.ic  larval stages of insects, crustaceans,
worms,  mollusks) as the biological indicator
of a stream's ecological condition. Benthic
macroinve"tebratcs live throughout the stream
bed, attaching to rocks and woody debris and
burrowing in sandy stream bottoms and among
the debris, roots, and grasses that collect and
                     o
grow along the water's edge (Figure 12). The
                    StonefIL
                  Dragornflies,
                  Damfelflies
                                                                              disflies
     Figure 12.  Stream macroinvertebrates (Photo courtesy of Maine Department of Environmental
     Protection). Macroinvertebrates in streams serve as the basis for the indicators of biological condition
     for the WSA.
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                                                        Chapter I   Design of the Wadeable Streams Assessment
 WSA focuses on these macroinvertebrates
 because of rheir inherent capacity ro integrate
 the effects of  the stressors to which  they are
 exposed, in combination and over time. Stream
 macroinvertebrates generally cannot move very
 quickly or very far; therefore, they are affected by,
 and may recover from, a number of changes in
 physical conditions (e.g., habitat loss), chemical
 conditions (e.g., excess nutrients), and biological
 conditions (e.g., the presence ol invasive or non-
 native species). Some types of macromvertebrares
 are affected by these conditions more than others.

   Macroinvertebrates provide a measurement
 of biological condition or health relative to
 the biological integrity of a stream.  Biological
 integrity represents the capability of supporting
 and maintaining a balanced, integrated,
 adaptive community of  organisms having a
 species composition, diversity, and functional
 orgam/ation comparable to that of  the natural
 habitat of the region. Macroinvertebrares are-
 researched by almost every state and federal
 program that  monitors streams and are also
 increasingly evaluated  by volunteer  orgam/.ations
 that monitor  water quality. In addition, water
 quality monitoring and  management programs
 are enhancing the understanding of the biological
 condition of streams by  adding other biological
 assemblages, including fish and algae.

   The WSA supplements information on
 the biological condition of streams with
 measurements of key stressors that might
 negatively influence or affect stream condition.
 Stressors are the chemical, physical,  and biological
components of the ecosystem that have the
potential to degrade stream biology. Some
stressors are naturally occurring, whereas others
 result only from human activities, although most
 come from both sources.

   Most physical stressors are created when we
 modify the physical habit.it of a stream or its
 watershed, such as through extensive urban or
 agricultural development, excessive upland or
 bank erosion, or loss of streamside trees and
 vegetation. I'.xamples of chemical stressors  include
 toxic compounds (e.g., heavy metals, pesticides),
 excess nutrients (e.g., nitrogen and phosphorus),
 or acidity from acidic deposition or mine
 drainage. Biological stressors are characteristics of
 the biota that can influence biological  integrity,
 such as the proliferation of non-native or invasive-
 species (either in the streams and  rivers, or in  the
 riparian areas adjacent  to these waterbodies).

   The WSA water chemistry data allow  an
 evaluation of  the distribution of nutrients,
 salinity, and acidification in U.S. streams. The
 physical habitat data provide information on the
 prevalence of  excess sediments,  the quality  of
 in-stream fish habitat, and the quality of  riparian
 habitat alongside streams. Although these are
 among the key stressors identified  by states as
 affecting water quality,  they do  not reflect the  full
 range of potential stressors that can impact water
 quality, future water quality surveys will  include
 an assessment ol additional stressors.

   One of the key components of an ecological
 assessment is a measure of how important (e.g.,
 how common) each stressor is within a region
                                        O
and how severely it affects biological condition.
                               O
 In addition to looking at  the extent of streams
affected by key stressors, the WSA evaluated the
relative risk posed by key stressors to biological
condition.
                                     The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter I   Design of the Wodeob/e Streams Assessment
      Highlight

      Understanding Biological Condition

        The main goal of the WSA is to develop a baseline understanding of the biological condition of
      our nation's streams. Why is this important?

        One of the most meaningful ways to answer basic questions about water quality is to directly
      observe the communities  of plants and animals that live in waterbodies. Aquatic plants and
      animals—especially the small creatures that are the focus of this study—are constantly exposed
      to the effects of various stressors; therefore, they reflect not only current conditions, but also the
      cumulative impacts of stresses and changes in conditions over time.

        Benthic macroinvertebrates are widely used to determine biological condition. These organisms
      can  be found in all streams, even in the smallest streams that cannot support fish. Because they
      are  relatively stationary and cannot escape pollution, macroinvertebrate communities integrate the
      effects of stressors over time (i.e., pollution-tolerant species will  survive in degraded conditions,
      and pollution-intolerant species will die). These communities are also critically important to fish
      because most game and non-game species require a good supply  of benthic macroinvertebrates
      as food. Biologists have been studying the health and composition of benthic macroinvertebrate
      communities in streams for decades.

        Biological condition is the most comprehensive indicator of waterbody health; when the biology
      of a stream is healthy, the  chemical and physical components of the stream are also typically in
      good condition. In fact, several states  have found that biological data frequently detect stream
      impairment where chemistry data do not.

        Data on biological condition are invaluable for managing the nation's aquatic resources and
      ecosystems.Water quality managers can use these data to set protection and restoration goals,
      decide which indicators to monitor and how to interpret monitoring results, identify stresses
      to the waterbody and decide how they should  be controlled, and assess and report on the
      effectiveness of management actions.  In fact, many specific state responsibilities  under the CWA—
      such as determining the extent to which waters support aquatic  life uses, evaluating cumulative
      impacts from polluted runoff, and determining the effectiveness of discharger permit controls—are
      tied directly to an understanding of biological condition.
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                                                      Chapter I    Design of the Wadeable Streams Assessment
Setting Expectations

   To interpret the data collected and assess
current ecological condition, chemical, physical,
and biological measurements must he compared
to a benchmark or estimate of what one would
expect to find in a natural condition. Setting
reasonable expectations lor an indicator is one of
the irreatest challenges to makmu an assessment ol
    o             o           o
ecological condition.  Should we take an historical
     O
perspective and  try to compare current conditions
to an estimate of pre-colomal conditions, pre-
indtistnal conditions, or conditions at  some other
point in history, or should we accept that some
level of anthropogenic disturbance is expected
and simply use the best of todays conditions as
the benchmark against which everything else is
compared?

    These questions, and their answers,  all relate
to the concept of reference condition. What
do we use as a reference condition to set the
A researcher collects macroinvertebrate samples
from a small stream in the Northern Appalachians
ecoregion (Photo courtesy of the Vermont Department
of Environmental Conservation).
 benchmark for assessing the current status of
 these waterbodies?  Because of the difficulty of
 estimating historical conditions for many of
 the WSA indicators, the assessment  used the
 conditions at a collection of "least-disturbed"
 sites as the reference condition.  This means
 that the condition at these sites  represents  the
 best available chemical, physical, and biological
 habitat conditions given the current state of the
 landscape. Least-disturbed sites  were identified
 by evaluating data collected at sites according to a
 set of explicit screening levels that define what  is
 least disturbed by human activities. To reflect the
 natural variability across the American landscape,
 these levels varied among the nine ecoregions.
 The WSA compared physical and chemical data
 collected at each  site (e.g., nutrients, riparian
 condition, chloride, turbidity, fine sediments)
 to the screening levels to determine whether any
 given site was in  least-disturbed  condition  for its
 ecoregion.

   Data on land use in the watersheds were not
 used to screen-out sites. l;or example, sites  in
 agricultural areas with effective best  management
 practices (BMI's) may have been considered least
 disturbed, provided they exhibited chemical and
 physical conditions that were among the best
 for their region.  The WSA also did not use data
 on biological assemblages as a screening factor
 to select reference sites because that would  have
 pre-judged expectations for biological condition.
 Similarly, when selecting least-disturbed reference
 sues for each stressor, the  WSA excluded the
 specific stressors themselves from the screening
 process.

   The WSA screening process resulted in the
 identification ol a set of least-disturbed reference
sites  for each WSA ecoregion.  I hese sites were
distributed throughout the ecoregions and
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Chapter I    Design oftheWadeable Streams Assessment
covered the range of natural variability across
each area. Some of these sites included a degree of
human-caused variability.

   The results from samples collected at  the
reference sites for the' various indicators (e.g.,
biological condition,  nutrients) represent the
range of expected values for least-disturbed
reference condition. I he WSA used this reference
distribution as a benchmark for setting thresholds
between good, fair, and poor condition.  These
thresholds were then applied to the random sites
to generate the percentage of stream length in
each condition class.

   The WSA's approach examined the range
of values for indicators in all of the reference
sites in a region and used the 5th percentile of
the reference distribution for that indicator to
separate the poor sites from fair sites. Using
the 5th  percentile means that stream sites and
associated stream length in poor condition
were worse than 95% of the sites used to define
least-disturbed reference condition. Similarly,
the 25th percenrile of the reference distribution
was used to distinguish between sites in fail' and
good condition. This means that stream  length
reported as being in good condition was as good
as or better than 75% of the sites used to define
least-disturbed reference condition.

   Within the reference site population,  there
exist two sources of variability: natural variability
and variability due  to human activities. Natural
variability—the wide range of habitat types
naturally found within each ecoregion—creates
a spread of reference sites representing these
differing habitats. Capturing natural variability in
reference sites helps establish reference conditions
that represent the range of environments in the
ecoregions.
   1 he second source of variation within the
reference population is change resulting from
human activities. Many areas in the United
Slates have been altered, with natural landscapes
transformed by cities, suburban sprawl,
agricultural development, and resource extraction.
'I he extent of those disturbances varies across
regions. Some of the regions of the country have
reference sites in watersheds with little to no
evidence ol human impact, such as mountain
streams or streams in areas with very low
population densities. Other regions of the country
have few sites that have not been influenced by
human activities. The least-disturbed reference
sues in these  \\idcly influenced watersheds
display more variability in quality than those in
watersheds with little human  disturbance.

   Variation within the reference distribution due
to disturbance was addressed before benchmarks
were set fot the' condition classes of good, fair,
and poor. I or regions where the reference sites
exhibited a disturbance signal, the data analysis
team accounted for this disturbance by shifting
the mean of the distribution toward the less-
disturbed reference sites.

   At a national meeting to discuss data analysis
options, WSA collaborators supported this
reference condition-based approach, which is
consistent with EPA guidance and  state practice
on the development of biological and nutrient
criteria. Additional details on how  the least-
disturbed condition anc benchmarks for the
condition categories were established for the
WSA can be  foand in the data analysis method
available on the  EPA Web site at http://wwvv.epa.
go\7owow/st ream survey.
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 Chapter 2
Condition of the Nation's
Streams

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Chapter 2    Condition of the Nation's Streams
Condition of the

Nation's  Streams

Background

  The CWA explicitly aims "to restore and
maintain the chemical, physical, and biological
integrity of the nation's waters." The WSA
examines these three aspects of water quality
through a small set of commonly used and widely
accepted indicators. Although this WSA report
does not include all aspects of biological integrity
or review all possible chemical, physical, or
biological stressors known to affect water quality,
it does present the results of important indicators
for an entire class of water resources—wadeable,
perennial streams.

  This chapter describes the results of the WSA
and is organized as follows:

 • Indicators of Biological Condition   Provides
   a description of the indicators or attributes of
   biological condition that were measured by the
   WSA survey and the results of the data analysis.
 * Aquatic Indicators of Stress - Presents
   findings on the stressors evaluated for the
   study.
 * Ranking of Stressors — Presents an analysis
   of the relative importance of the stressors in
   affecting biological condition.

   Results for each indicator are shown for the
nation's streams and for the three major regions
(Pastern I lighlancls, Plains and Lowlands, and
West). Chapter 3 of this report presents indicator
results for each of the nine WSA ecoregions.


Indicators of Biological
Condition

   Kcologists evaluate the biological condition of
water resources, including wadeable streams, by
analy/ing key characteristics of the communities
of organisms that  live in these waterbodies.
    O
These characteristics include the composition
and relative abundance of key groups of animals
(e.g., hsh and invertebrates) and plants (e.g.,
periphyton, or algae that attach themselves
to stream bottoms, rocks, and woody debris)
                  Jellison Meadow Brook, ME, in the Eastern Highlands region
                  (Photo courtesy of Colin Hill,TetraTech, Inc.).
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                                                              Chapter 2   Condition of the Nation's Streams
found in streams. I he WSA focused on just one
assemblage, benthic macromvertebrates (e.g.,
aquatic  insects, crustaceans, worms and mollusks);
however, some WSA participants also  researched
other assemblages.

   Why focus on macroinvertebrates?  Macro-
invertebrates are key organisms that reflect the
quality  of their environment and respond to
human  disturbance in fairly predictable ways.
As all fly-fishermen know, the  insects emerging
from  streams and rivers are good indicators of
the water quality and serve as an important
food source for both game and non-game fish.
                    O              O
Given the wide geographic distribution of
macroinvertebrates, as well as their abundance
and link to fish and other aquatic vertebrates,
these  organisms serve as excellent indicators of the
quality  of flowing waters and the human stressors
that affect these systems.

   WSA researchers collected samples  of these
organisms and sent them to laboratories for
analysis, yielding a data set that provided the
types  and number of taxa (i.e., classifications
or groupings of organisms) found at each
site. To  interpret this data set,  the WSA used
two indicators of biological condition: the
Macroinvcrtcbrate Index of Biotic Condition  and
the Observed/Hxpected (O/K)  Ratio of Taxa Loss.

Macroinvertebrate Index
of Biotic  Condition
   The  Macroinvertebrate Index of Biotic
Condition (henceforth referred to as the
Macroinvertebrate Index) is similar  in concept
to the economic Consumer Confidence Index
(or the Leading Index of  Economic  Indicators)
in that the total  index score is the sum of
scores for a variety of individual measures, also
   What are Taxa?

     Taxa (plural of taxon) are groupings of living
   organisms, such as phylum, class, order, family, genus,
   or species. Biologists scientifically describe and
   organize organisms into taxa in order to better
   identify and understand them.
called indicators or metrics. To determine the
Leading Index, economists look at a number of
      O
metrics, including manufacturers' new orders
for consumer goods, building permits, money
supply, and other aspects of the economy that
reflect economic growth. To determine the
Macroinvcrtebrate Index, ecologists look at such
metrics as taxonomic richness, habit and trophic
composition, sensitivity to human disturbance,
and other biotic aspects that reflect "naturalness."
Originally developed as an Index of Biotic
Integrity for fish in Midwestern streams, the
Macroinvertebrate Index has been modified and
applied to other regions, taxonomic groups, and
ecosystems.

   The metrics used to develop the Macro-
invcrtcbrate Index for the WSA covered six
different characteristics of macroinvertebrate
assemblages that are commonly used to evaluate
biological condition:

 • Taxonomic richness — I his characteristic
   represents the number of distinct taxa, or
   groups of organisms, identified within a
   sample. Many different kinds of distinct taxa,
   particularly those that belong to pollution-
   sensitive insect groups, indicate a variety of
   physical habitats and food sources and an
   environment exposed to generally lower  levels
   of stress.
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Chapter 2   Condition of the Nation's Streams
        Using Multiple Biological Assemblages to Determine Biological Condition

           EPA's guidance on developing biological assessment and criteria programs recommends the
        use of multiple biological assemblages to determine biological condition. The term "multiple
        biological assemblages" simply refers to the three main categories of life found in a waterbody:
        plants (e.g., algae), macroinvertebrates, and vertebrates (e.g., fish). The purpose of examining
        multiple biological assemblages is to generate a broader perspective of the condition of the
        aquatic resource of interest.

           Each assemblage plays a different role in the way that rivers and streams function. Algae
        and macroinvertebrates occur throughout all types and sizes of streams, whereas very small
        streams may be naturally devoid offish. Algae are the  base of the food chain and capture
        light and nutrients to generate energy. They are sensitive to changes in shading, turbidity, and
        increases or decreases in nutrient levels.  Macroinvertebrates feed on algae and other organic
        material that enters the aquatic system from the surrounding watershed. Macroinvertebrates
        also form the base of the food chain for many aquatic vertebrates. Fish are an  example of
        these aquatic vertebrates and also serve as an important food source for people and wildlife.
        Each of these groups of aquatic organisms is sensitive in its own way to different human-
        induced disturbances.

           TheWSA collaboration  began as a partnership among  12 western states; EPA Regions 8,
        9, and 10; and EPA's Western  Ecology Division (Environmental Monitoring and Assessment
        Program [EMAP] West) before it was expanded to include the entire United States.  The
        original EMAPWest program addressed fish, macroinvertebrates, and algae; future WSA reports
        will also address multiple assemblages.

           To learn more about EMAPWest and its use of multiple biological assemblages, visit www.
        epa.gov/emap/west/index.html.
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                                                             Chapter 2   Condition of the Nation's Streams
• Taxonomic composition  Ideologists
  calculate composition metrics by identifying
  the different taxa groups, determining which
  taxa in the sample are ecologically important,
  and comparing the relative abundance of
  organisms in those taxa to the whole sample.
  Healthy stream systems have organisms from
  across many different taxa groups, whereas
  unhealthy stream systems are often dominated
  by a high abundance of organisms in a small
  number of taxa that arc tolerant of pollution.
• Taxonomic diversity - Diversity metrics look
  at all the taxa groups and the distribution
  of organisms among  those groups. Healthy
  streams should have a high level of diversity
  throughout the assemblage.
• Feeding groups - Many macroinvertcbrar.es
  have specialized strategies to capture and
  process food from their aquatic environment.
  As a stream degrades from its natural
  condition, the distribution of animals among
  the different feeding  groups will change. For
  example, as a stream  loses its canopy (a source
  of leaves and shading), the aquatic community
  will shift from a more diverse food chain to
  one of predominantly algal-feeding animals
  that arc tolerant of warm water.
• Habits — Just like other organisms, benthic
  macroinvertebratcs are characterized by
  certain habits,  including how they move and
  where they live. These habits are captured
  in the habit metrics.  For example, some
  taxa burrow under  the streambed sediment,
  whereas others cling to rocks and debris within
  the stream channel. A stream that naturally
  includes a diversity of habitat types will
  support animals with diverse habits; however,
  if a stream becomes laden with silt, the
   macroinvertebrar.es that cling, crawl, and swim
   will be replaced by those that burrow.
 • Pollution tolerance— Each macroinvertebrate
   taxa can tolerate a specific range of stream
   contamination, which is referred to as
   their pollution tolerance. Once this level is
   exceeded, the taxa are no longer present in that
   area of the stream. Highly sensitive  taxa, or
   those with a low pollution tolerance, are found
   only in streams with good water quality.
   The specific metrics chosen for each of these
categories varied among the nine ecorcgions used
in  the analysis. Fach metric was scored and then
combined to create an overall Macroinvertebrate
Index for each region, with values ranging from
0 to  100. For the WSA, analysts calculated  a
Macroinvertebrate Index score for each site,
factored in the stream length represented by the
site, and  then generated an estimate of the stream
length  in a region,  and nationally, with a given
Macroinvertebrate Index score.
 Six different characteristics of macroinvertebrate
 assemblages are commonly used to evaluate
 biological condition in wadeable streams (Photo
 courtesy of Lauren Holbrook, IAN Image Library).
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Chapter 2   Condition of the Nation's Streams
Findings for the Macroinvertebrate Index
of Biotic Condition
   As illustrated in Figure 13, the Macroinverte-
brate Index indicator results show that 42% of
the nation's stream length (281,170 miles) is
in poor condition, 25% (167,092 miles) is in
fair condition, and 28% (189,236  miles) is in
good condition compared to the least-disturbed
reference condition in each of the nine WSA
ecoregions. The 28% of stream length in good
condition has conditions most similar to the
reference distribution derived from the best-
available (least-disturbed) sites in each ecoregion.
The 5% (33,553 miles) of unassessed stream
length results from the fact that  Ist-order streams
in New England were not sampled for the WSA.

   Macroinvertebrate Index results show that
the Eastern Highlands region has the highest
proportion of stream length (52%, or 143,170
miles)  in poor condition, followed  by the Plains
and Lowlands (40%, or 96,905 miles) and the
West (27%, or 41,754 miles).
                                                                         Stream Length (mi)
                 National
                (lower 48)
                                     10
                                                                        60
                                            20      30      40
                                          Percentage of Stream Miles
                              • Good  D Fair  H Poor  D Not Assessed
Figure 13. Biological condition of streams based on Macroinvertebrate Index of Biotic Condition
(U.S. EPA/WSA). The Macroinvertebrate Index combines metrics of benthic community structure and function
into a single index for each region. The thresholds for defining good, fair, and poor condition were developed for
each of the nine WSA ecoregions based on condition at the least-disturbed reference sites. Stream length in good
condition is most similar to least-disturbed reference condition; in fair condition has Macroinvertebrate Index
scores worse than 75% of reference condition; and in poor condition  has Macroinvertebrate Index scores worse
than 95% of reference condition.
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                                                                Chapter 2    Condition of the Nation's Streams
   What are Confidence Intervals?

      Confidence intervals (i.e., the small lines at the end of the bars in this report's charts) are provided to convey the
   level of certainty or confidence that can be placed in the information presented in this report. For example, for the
   national Macroinvertebrate Index, the WSA finds that 28.2% of the nation's stream length is in good condition, and the
   confidence is +/- 2.8%, which means that there is a 95% certainty that the real value is between 25.4% and 3 I %. The
   confidence interval depends primarily on the number of sites sampled; as more streams are sampled, the confidence
   interval becomes narrower, meaning there is more confidence in the findings. When fewer streams are sampled, the
   confidence interval become  broader, meaning there is less certainty in the findings. Figure 13 shows an example of this
   pattern, in which the confidence interval for the national results (the largest sample size) is narrowest, whereas the
   confidence intervals for the  major regions, where a smaller number of streams were sampled, are generally broader.
   Ultimately the breadth of the confidence interval is a tradeoff between the need for increased certainty to support
   decisions and the money and resources dedicated to monitoring.
Macroinvertebrate  Observed/
Expected (O/E) Ratio ofTaxa
Loss
   The Macroinvertebrate O/E Ratio ofTaxa
Loss (henceforth referred to as O/KTaxa Loss)
measures a specific aspect of biological health:
taxa that have been lost at a site. The taxa
expected (E) at individual sites are predicted
trom a model developed from data collected at
least-disturbed reference sites; thus,  the model
allows a  precise matching of sampled taxa with
those that should occur under specific, natural
environmental conditions. By comparing the list
of taxa observed (O) at a site with those expected
to occur, the proportion of expected taxa that
have been lost can be quantified as the ratio of O/
L. Originally developed for streams  in the United
Kingdom, O/E Taxa Loss models are modified
for the specific natural conditions in each area
for which they are used. The O/E Taxa Loss
indicator is currently used by several countries
and numerous states in the United States.
   O/E Taxa Loss values range from 0 (none of
the expected taxa are present)  to slightly greater
than 1  (more taxa are present than expected).
These values are interpreted as the percentage of
the expected taxa present. Each tenth of a point
less than 1 represents a 10% loss of taxa at a site;
thus, an O/E Taxa Loss score of 0.9 indicates
that 90% of the expected taxa are present and
10% are missing. O/E Taxa Loss values  must
be interpreted in the context of the quality of
reference sites used to build the predictive models,
because the quality of reference sites available in
a region sets the bar for what is expected (i.e.,
regions with lower-quality reference sites will
have a lower bar). Although an O/E Taxa Loss
value of 0.8 means the same thing regardless of
a region (i.e., 20% of taxa have been lost relative
to reference conditions in each region),  the true
amount of taxa loss will be underestimated if
reference sites are of low quality.

   The WSA developed three O/E Taxa  Loss
models to predict the extent of taxa loss across
streams of the United States, one model for each
of the three major regions outlined in this report
(Eastern Highlands, Plains and  Lowlands, West).
Analysts used the O/E Taxa Loss scores observed
at each site to generate estimates of the nation's
stream length estimated to fall  into four categories
of taxa loss.
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Chapter 2   Condition of the Nation's Streams

   Although in many cases the results of O/E
Taxa Loss analysis are similar to the results of the
Macroinvcrtebrate Index, such agreement will
not always occur. The O/E Taxa Loss indicator
examines a specific aspect of biological  condition
(biodiversity loss), whereas the Macroinvertebrate
Index combines multiple characteristics. For
the WSA, the two indicators provided similar
results in those WSA ecoregions that had a lower
disturbance signal among their reference sites.

Findings for O/E Taxa Loss
   Figure 14 displays the national and regional
O/E Taxa Loss summary. These data are presented
in four categories: (1) less than  10% taxa loss,
(2) 10-20% taxa loss, (3) 20-50% taxa loss, and
                 National
                (lower 48)
(4) more than 50% taxa loss. Forty-two percent
of the nation's stream length retained more than
90% of expected taxa; 1.3% lost 10-20% of taxa;
26% lost 20-50% of taxa; and 13% lost more
than 50% of taxa.

  Within the three regions, stream length in
the Eastern Highlands experienced the greatest
lo.ss of expected taxa, with 17% experiencing
a loss of 50% or more. An additional 29% of
stream length  in this region lost 20—50% of
taxa; 13% lost 10-20% of taxa; and only 28%
of stream length lost fewer than  10% of taxa.
Eleven percent of stream  length in the Plains and
Lowlands region experienced a taxa loss of 50%
or more, 25% of stream length lost 20—50% of
                                          20
                                                                                  90   100
                                               30    40     50     60    70   80
                                                  Percentage of Stream Miles
                               H > 50% Taxa toss   Q 20-50% Taxa _oss
                               D  10-20% Taxa Loss • < 10% Taxa toss  D Not Assessed
 Figure  14. Macroinvertebrate taxa loss as measured by the O/E Ratio of Taxa Loss (US. EPA/WSA).
 The O/E Taxa Loss indicator displays the loss of taxa from a site compared to reference for that region.
 Scores O.I lower than reference represent a 10% loss in taxa.
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raxa; 13% lost 10-20% of taxa; and 47% lost
fewer than  10% of taxa. In the West, 7% of
stream length experienced a raxa loss of 50% or
more, 21% of stream length lost 20-50% of taxa;
10% lost 10-20% of taxa; and 58% of stream
length lost  less than 10% of taxa.


Aquatic  Indicators of Stress
   As people use the landscape,  their actions
can produce effects that are stressful to aquatic
ecosystems. These aquatic stresses can be
chemical, physical, or in some cases, biological.
The WSA has selected a short list of stressors
from each of these categories as indicators for
assessment. This list is not intended to be all-
inclusive, and in fact, some important stressors
are not included because there is currently no
way to assess them at the site scale (e.g.,  water
withdrawals for irrigation). Future assessments
of U.S. stream and river condition will include a
more comprehensive list of stressors from each of
these categories.
   WSA indicators are based on direct measures
of stress in  the stream or adjacent riparian areas,
not on land use or land cover alterations, such
as row crops, mining,  or gra/mg. Many human
activities and land uses can be sources of one
or more stressors to streams; however, the WSA
only assesses stressors to determine  the general
condition of the resource and which stressors are
most significant and does not track the source of
these stressors. Source tracking, an expensive and
time-consuming process,  is a logical future step
for the WSA and similar national assessments.
       Chapter 2    Condition of the Nation's Streams

   A summary of the national and regional results
for indicators of chemical and physical habitat
are shown in figures 15 through 22. WSA results
for these  indicators for each of the nine WSA
ecoregions are presented in Chapter 3 of this
report.

Chemical Stressors
   Tour chemical stressors were assessed as
indicators in the WSA: total phosphorus, total
nitrogen, salinity, and acidification. These
stressors were selected because of national or
regional concerns about the extent to which
each might be impacting the quality of stream
biota. The thresholds for interpreting data were
developed from a set of least-disturbed reference
sites for each of the  nine WSA ecoregions, as
described in Chapter 1, Setting /Expectations. The
results for each ecoregion were tallied to report
on conditions  for the three major regions and the
entire nation.

Total Phosphorus Concentrations
   Phosphorus is usually considered the most
likely nutrient limiting algal gtowth in U.S.
freshwater waterbodics. Because of the naturally
low concentrations of phosphorus in stream
systems, even small  increases in phosphorus
concentrations can impact a stream's water
quality. Some waters—such as streams originating
from eroundwater in volcanic areas of eastern
     O
Oregon and Idaho—have naturally higher
concentrations of phosphorus. This natural
variability is reflected in the regional thresholds
for high,  medium, and low, which are based on
the least-disturbed reference sites for each of the
                                                      nine WSA ecoregions.
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Chapter 2    Condition of the Nation's Streams
      Nutrients and Eutrophication in Streams

        Eutrophication is a condition characterized by excessive plant growth that results from high
      levels of nutrients in a waterbody. Although eutrophication is a natural process, human activities
      can accelerate this condition by increasing the rate at which nutrients and organic substances enter
      waters from their surrounding watersheds. Agricultural runoff, urban runoff, leaking septic systems,
      sewage discharges, eroded streambanks, and similar sources can increase the flow of nutrients and
      organic substances  into streams, and subsequently, into downstream lakes and estuaries. These
      substances can overstimulate the growth of algae and aquatic plants, creating eutrophic conditions
      that interfere  with recreation and the health and diversity of insects, fish, and  other aquatic
      organisms.

        Nutrient enrichment due to human activities has long been recognized as one of the leading
      problems facing our nation's lakes, reservoirs, and estuaries. It has also been more recently
      recognized as a contributing factor to stream degradation. In broadest terms, nutrient over-
      enrichment of streams is a problem because of the negative impacts on  aquatic: life (the focus of
      the WSA);adverse health effects on humans and domestic animals; aesthetic and recreational use
      impairment; and excessive nutrient input into downstream waterbodies, such  as lakes.

        Excess nutrients in streams can lead to  excessive growth of phytoplankton (free-floating
      algae) in slow-moving rivers, periphyton  (algae attached to the substrate) in shallow  streams, and
      macrophytes (aquatic plants large enough to be visible to the naked eye) in all waters.  Unsightly
      filamentous algae can impair the  aesthetic enjoyment of streams. In more extreme situations,
      excessive growth of aquatic  plants can slow water flow in flat streams and canals, interfere with
      swimming, snag fishing lures, and clog the screens on water intakes of water treatment plants and
      industries.

        Nutrient enrichment in streams has also been demonstrated to affect animal communities in
      these waterbodies (see the References section at the end of this report for examples of published
      studies). For example, declines in invertebrate community structure have been correlated directly
      with  increases in phosphorus concentration. High concentrations of nitrogen in the form of
      ammonia (NH3) are known to be toxic to aquatic animals.  Excessive levels  of algae have also been
      shown to be damaging to invertebrates.  Finally, fish and invertebrates will experience growth
      problems and can even die if either  oxygen is depleted or pH increases are severe; both of these
      conditions are symptomatic of eutrophication.

        As a system becomes more enriched by nutrients, different species of algae may spread and
      species composition can shift; however, unless such species shifts cause clearly demonstrable
      symptoms of poor water-quality—such as  fish kills, toxic algae, or very long streamers of
      filamentous algae—the general public is  unlikely to be aware of a potential ecological concern.
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   Phosphorus influx leads to increased algal
growth, which reduces dissolved oxygen levels and
water clarity within the stream. (Sec Highlight:
Nutrients and Eutrophication in Streams for
more information about the impacts of excess
phosphorus and nitrogen.) Phosphorus is a
common component of fertilizers, and high
phosphorus concentrations in streams may be
associated with poor agricultural practices,  urban
runoff, or point-source discharges (e.g., effluents
from sewage treatment plants).
           National
          (lower 48)
        Chapter 2   Condition of the Nation's Streams

Findings for Total Phosphorus
   Approximately 31% of the nation's stream
length (207,355 miles) has high concentrations
of phosphorus, 16% (108,039 miles) has medium
concentrations, and 49% (327,473 miles) has
low concentrations (Figure 15). Of the three
major regions, the Eastern Highlands has the
greatest proportion of stream length with high
concentrations of phosphorus (43%, or 1 17,730
miles), followed by the Plains and Lowlands
(25%, or 60,324 miles) and the West (19%, or
28,174 miles) regions.
                                                                    Stream Length (mi)
                                                             60
                                                                   70
                                    20    30     40     50
                                     Percentage of Stream Miles
                          I Low D Medium H High  CU Not Assessed
Figure  15. Total phosphorus concentrations in U.S. streams (U.S. EPA/WSA).  Percent of stream length
with low, medium, and high concentrations of phosphorus based on regionally relevant thresholds derived
from the least-disturbed regional reference sites. Low concentrations are most similar to reference condition;
medium concentrations are greater than the 75th percentile of reference condition; and  high concentrations are
greater than the 95th percentile of reference condition.
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Chapter 2   Condition of the Nation's Streams

Total Nitrogen Concentrations
   Nitrogen, another nutrient, is particularly
important as a contributor to coastal and
estuarine algal blooms. Nitrogen is the primary
nutrient limiting algal growth in some regions
of the United States, particularly in granitic or
basaltic geology found in parts of the Northeast
and the Pacific Northwest. Increased nitrogen
inputs to a stream can stimulate growth of excess
algae, such as periphyton, which results in low
dissolved oxygen  levels, a depletion of sunlight
available to the streambed, and degraded habitat
conditions for benthic macroinvertebrates and
                  National
                 (lower 48)
other aquatic life (see Highlight: Nutrients and
Eutrophication in Streams). Common sources of
excess nitrogen include fertilizers, wastcwater,
animal wastes, and atmospheric deposition.
Findings for Total Nitrogen
   A significant portion of the nation's stream
length (32%, or 213,394 miles) has high
concentrations of nitrogen compared to least-
disturbed reference conditions, 21% (138,908
miles) has medium concentrations, and 43%
(290,565 miles) has relatively low concentrations
(Hgure 16). As with phosphorus, the Eastern
                                                                           Stream Length (mi)
                                      10
                                                                   50
                                             20      30      40
                                            Percentage of Stream Miles
                               • Low  D Medium HI High D Not Assessed
Figure 16. Total nitrogen concentrations in U.S. streams (U.S. EF'A/WSA).  Percent of stream length
with low, medium, and high concentrations of nitrogen based on regionally relevant thresholds derived from the
least-disturbed regional reference sites. Low concentrations are most similar to reference condition; medium
concentrations are greater than the 75th percentile of reference condition; and high concentrations are greater
than the 95th percentile of reference condition.
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                                                               Chapter 2    Condition of the Nation's Streams
Highlands region has the greatest proportion
of stream length with high concentrations of
nitrogen (42%, or 117,284 miles), followed by
the Plains and Lowlands (27%, or 65,71 5 miles)
and the West (21%, or 31,247 miles).

Salinity
   Excessive salinity occurs in areas with high
evaporative losses of water and can be exacerbated
by repeated use of water for irrigation or by
water withdrawals. Both electrical conductivity
and total dissolved solids (TDS) can be used as
measures of salinity; however, conductivity was
used for the WSA.
Findings for Salinity
   Roughly 3% of the nation's stream length
(19,889 miles) has high levels of salinity, 10%
(69,585 miles) has medium levels, and 83%
(553,530 miles) has low levels compared to levels
found in least-disturbed reference sites for the
nine WSA  ecoregions (Figure 17). The Plains
and Lowlands region  has the greatest proportion
of stream length with high levels of salinity (5%,
or 12,113 miles), followed by the West (3%,
or 4,009 miles) and Eastern Highlands (1%, or
3,593 miles).
                                                                           Stream Length (mi)
                 National
                (lower 48)
                                  10  20
                                                                 80  90   100
                                           30   40   50   60   70
                                           Percentage of Stream Miles
                              I Low  D Medium  H High D Not Assessed
   Figure  17. Salinity conditions in U.S. streams (U.S. EPA/WSA). This indicator is based on electrical
   conductivity measured in water samples. Thresholds are based on conditions at least-disturbed regional
   reference sites.
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Chapter 2    Condition of the Nation's Streams
Acidification
   Streams and rivers can become acidic through
the effects of acid deposition (e.g., acid rain) or
acid mine drainage, particularly from coal
mining. Previous studies have shown that these
issues, while of concern, tend to be focused in a
few geographic regions of the country. Streams
and rivers can also be acidic because of natural
sources, such as high levels of dissolved organic
compounds. The WSA identifies the extent of
systems that are not acidic, naturally acidic (i.e.,
similar to reference), and acidic because of
anthropogenic disturbance. This last category
includes streams that are acidic because of
deposition (either chronic or episodic) or because
of mine drainage.

   Acid rain forms when smokestack and
automobile emissions (particularly sulfur dioxide
and nitrogen oxides) combine with moisture in
the air to form dilute solutions  of sulfuric and
nitric acid. Acid deposition can also occur in dry
form, such as the particles that  make up soot.
When wet and dry deposition fall on sensitive
watersheds, they can have deleterious effects on
soils, vegetation, and streams and rivers.

   In assessing acid rain's effects on flowing
waters, the WSA relied on a measure of the
water's ability to buffer inputs of acids, called
acid-neutralizing capacity (ANC).  When ANC
values fall below zero, the water is  considered
acidic and can be either directly or indirectly
toxic to biota (i.e., by mobilizing toxic merals,
such as aluminum). When ANC is between 0
and 25 milliequilivents, the water  is considered
sensitive to episodic acidification during  rainfall
events. These threshold values were determined
based on values derived from the National Acid
Precipitation Assessment Program  (NAPAP).
   Acid mine drainage forms when water moves
through mines and mine tailings, combining
with sulfur released from certain minerals to form
strong solutions of sulfuric acid and  mobilize
many toxic metals. As in the case of acid rain,
the acidity of waters in mining areas  can be
assessed by using ANC values. Mine drainage
also produces extremely high concentrations
of sulfate—much higher than those found in
acid rain. Although sulfate is not directly toxic
to biota, it serves as an indicator of mining's
influence cm streams and rivers. When ANC
values and sulfate concentrations are low, acidity
can be attributed to acid rain. When ANC values
arc low and sulfate concentrations arc high,
acidity can be attributed to acid mine drainage.
Mine drainage itself, even if not acidic, can  harm
aquatic life; however, the WSA does  not include
an assessment of the extent of mine drainage that
is not acidic.
Acidic mine drainage forms when water moves
through mines and mine tailings (Photo courtesy
of Ben Fertig, IAN Image Library).
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                                                                Chapter 2   Condition of the Nation's Streams
                                                                               Stream Length (mi)
                  National
                  (lower 48)
                                o
                                        20
                                                                   80   90  ! 00
                                             30   40   50   60  70
                                             Percentage of Stream Miles
                    • Good (not acidic) D Fair (naturally acidic)  H Poor (anthropogenically acidic) D Not Assessed
Figure 18. Acidification in U.S. streams (U.S. EPA/WSA).  Streams are considered acidic when ANC values
fall below zero. Streams are considered sensitive to acidification during rainfall events when ANC values are
between 0 and 25 milliequilivents. Both ranges were scored as anthropogenically acidic in poor condition. Acidic
streams with  high concentrations of sulfate are associated with acid mine drainage, whereas low concentrations
of sulfate indicate acidification due to acid rain.
Findings for Acidification
   Figure 18 shows that about 2% of the nation's
stream length (14,763 miles) is impacted by
acidification from anthropogenic sources. These
sources include acid deposition (0.7%), acid
mine drainage (0.4%), and episodic acidicity
due to high-runoff events (1%). Although these
percentages appear relatively small, they reflect a
significant  impact in certain parts of the United
States,  particularly in the Eastern Highlands
region, where 3% of the stream length (9,396
miles) is impacted by acidification.
Physical Habitat Stressors
   A number of human activities can potentially
impact the physical habitat of streams upon which
the biota rely. Soil erosion from road construction,
poor agricultural practices, and other disturbances
can result in increases in the amount of fine
sediment on the stream bottom; these sediments
can negatively impact macroinvertcbrates and fish.
Physical alterations to vegetation along stream
banks, alterations to the physical characteristics
within the stream itself, and changes in the flow of
water all have the potential to impact stream biota.
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Chapter 2   Condition of the Nation's Streams
   Although many aspects of stream and river
habitats can become stressful to aquatic organisms
when these aspects are modified, the WSA focuses
on four specific stressors as habitat indicators:
streambcd sediments, in-stream fish habitat,
riparian vegetation, and riparian disturbance.

Streambed Sediments
   The supply of water and sediments from
drainage areas affects the shape of river channels
and the size of streambed particles in streams
and rivers. One measure of the interplay between
sediment supply and transport is relative bed
stability (RBS). The measure of RBS  used in
the WSA is a ratio that compares measures of
particle size of observed sediments to the size of
sediments that each stream can more or scour
during its flood stage (based  on measures of the
size, slope, and other physical characteristics of
the stream channel). The expected RBS ratio
differs naturally among regions, depending
upon landscape characteristics, such as geology,
topography, hydrology, natural vegetation, and
natural disturbance history.

   Values of the RBS ratio can be either
substantially lower (e.g., finer, more unstable
streambeds) or higher (e.g., coarser, more stable
strcambeds) than those expected, based on
the range found at least-disturbed reference
sites. Both high and low values are considered
to be indicators of ecological stress. Excess
fine sediments in a stream bed can destabilize
streams when the supply of sediments from the
landscape exceeds the ability of the stream to
move them downstream. This imbalance results
from a number of human  uses of the landscape,
including agriculture, road building,  construction,
and grazing. Streams with significantly more
soble streambeds than reference condition (e.g.,
evidence of hardening and scouring, streams that
have been lined with concrete) were not included
in the assessment of this indicator. These stream
conditions occurred so rarely in the survey that
it was not necessary to separate them from the
overall population. The WSA focuses on increases
in streambed sediment levels, represented by
lower-than-expected streambed stability as the
indicator of concern.

  Lower-than-expected streambed stability may
result either from high inputs of fine sediments
(e.g., erosion) or increases in flood magnitude
or frequency (e.g., hydrologic alteration).  When
low RBS results from inputs of fine sediment, the
sediment can fill in the habitat spaces between
stream cobbles and boulders. The instability
(low RBS) resulting from hydrologic alteration
can be a precursor to channel incision and gully
formation.
WSA researchers collected data on indicators
of biological condition and aquatic indicators of
stress at  1,392 wadeable stream locations in the
conterminous United States (Photo courtesy of
TetraTech, Inc.).
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                                                              Chapter 2   Condition of the Nation's Streams
Findings for Streambed Sediments
   Approximately 25% of the nation's stream
length (167,092 miles) has streambed sediment
characteristics in poor condition compared
to regional reference condition (Figure 19).
Streambed sediment characteristics arc rated fair
in 20% of the nation's stream length (132,197
miles) and good in 50% of stream length
(336,196 miles) compared to reference condition.
The two regions with the greatest percentage of
stream length in poor condition  for streambed
sediment characteristics are the Eastern Highlands
(28%, or 77,381 miles) and the  Plains and
                                                       Lowlands (26%, or 63,958 miles), whereas the
                                                       West has the lowest percentage of stream length
                                                       (17%, or 26,522 miles) in poor condition for this
                                                       indicator.

                                                       In-stream Fish Habitat
                                                         The most diverse fish and macroinvertebratc
                                                       assemblages are found in streams and rivers that
                                                       have complex forms of habitat, such as boulders,
                                                       undercut banks, tree roots, and large wood within
                                                       the stream banks. Human  use of streams and
                                                       riparian areas often results in the simplification of
                                                       this habitat, with potential effects on biological
                                                                           Stream Length (mi)
                  National
                 (lower 48)
                                     10
                                                                   60
                                                                         70
                                           20     30    40    50
                                            Percentage of Stream Miles
                               • Good  EH Fair  I Poor O Not Assessed
Figure  19. Streambed sediments in U.S. streams (U.S. EPA/WSA). This indicator measures the percentage
of streambeds impacted by increased sedimentation, which indicates alteration from reference condition as
defined by least-disturbed reference sites in each of the nineWSA ecoregions.
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Chapter 2   Condition of the Nation's Streams

integrity. The WSA used a habitat complexity
measure that sums the amount of in-stream fish
concealment features and habitat consisting of
undercut banks, boulders, large pieces of wood,
brush, and cover from overhanging vegetation
within a stream and  its banks.

Findings for In-stream Fish Habitat
   Twenty percent of the nation's stream length
(130,928 miles) is in poor condition for in-
stream fish habitat, 25% (166,851 miles) is in fair
condition, and 52% (345,766 miles) is in good
condition compared to least-disturbed reference
condition (Figure 20). In the three major regions,
                   National
                  (lower 48)
the highest proportion of stream length in poor
condition for in-stream habitat is in the Plains
and Lowlands (37%, or 89,638 miles), whereas
only 12% of stream length (18,748 miles) in the
West and 8% of stream length (22,797 miles) in
the Eastern Highlands region is rated  poor for this
indicator.

Riparian Vegetative Cover
   The presence of complex, multi-layered
vegetative cover in the corridor along  a stream or
river is a measure of how well the stream network
is buffered against sources of stress in  the
                                                                            Stream Length (mi)
                                      10
                                                                     60
                                                                           70
                                            20     30    40    50
                                             Percentage of Stream Miles
                                • Good  D Fair E9 Poor D Not Assessed
 Figure 20. In-stream fish habitat in U.S. streams (U.S. EPA/WSA). This indicator sums the amount of
 in-stream habitat that field crews found in streams.  Habitat consisted of undercut banks, boulders, large pieces
 of wood, and brush. Thresholds are based on conditions at regional reference sites.
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watershed. Intact riparian areas can help reduce
nutrient and sediment runoff from the
surrounding landscape, prevent streambank
erosion, provide shade to reduce water
temperature, and provide leaf litter and large-
wood to serve as food and habitat  for stream
organisms. The presence of large, mattire canopy
trees in the riparian corridor indicates riparian
longevity; the  presence of smaller woody
vegetation typically indicates that riparian
vegetation is reproducing and suggests the
potential for future sustainability of the riparian
corridor. 1 he WSA uses a measure of riparian
vegetative cover that sums the amount of woody
                  National
                 (lower 48)
        Chapter 2   Condition of the Nation's Streams

cover provided by three layers of riparian
vegetation: the ground layer, woody shrubs, and
canopy trees.
Findings for Riparian Vegetative Cover
   Nineteen percent of the nation's stream length
(129,748 miles) is in poor condition due to
severely simplified riparian vegetation, 28% of
stream length (190,034 miles) is in fair condition,
and almost 48% (319,548  miles)  is in good
condition relative to least-disturbed reference
condition in  each of the nine WSA ecoregions
(Figure 21). The West (12%, or 18,596 miles)
and Eastern Highlands (18%, or 48,640 miles)
                                                                             Stream Length (mi)
                                                                   50
                                                                          60
                                             20      30      40
                                            Percentage of Stream Miles
                               I Good  D Fair I Poor  CD Not Assessed
Figure 21. Riparian vegetative cover in U.S. streams (U.S. EPA/WSA). This indicator sums the amount of
woody cover provided by three layers of riparian vegetation: the ground layer, woody shrubs, and canopy trees.
Thresholds are based on conditions at regional reference sites.
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Chapter 2   Condition of the Nation's Streams
regions have similar proportions of scream length
with riparian vegetation in poor condition,
though this equates to a greater number of
stream miles in the Eastern Highlands region,
where water is more abundant. In the Plains and
Lowlands region, a larger proportion of stream
length (26%, or 62,881 miles) has riparian
vegetation in poor condition.
The most diverse fish and macroinvertebrate
assemblages are found in streams and rivers
that have complex forms of habitat, such as
boulders, undercut banks, tree roots, and
large wood within the stream banks (Photo
courtesy of Michael L Smith, F WS).
Riparian Disturbance
   The vulnerability of the stream network to
potentially harmful human activities increases
with the proximity of those activities to the
streams. The WSA uses a direct measure of
riparian human disturbance that tallies 11 specific
forms of human activities and disturbances
along the stream reach and their proximity to a
stream in 22 riparian plots along the stream. For
example, streams scored medium if one type of
human influence was noted in at least one-third
of the plots, and streams scored high if one or
more types of disturbance were observed in the
stream or on its banks at all of the plots.

Findings for Riparian Disturbance
   Twenty-six percent of the nation's stream
length (171,118 miles) has high levels of human
influence along the riparian zone that fringes
stream banks, and 24% of stream length (158,368
miles) has relatively low levels of disturbance
(Figure 22). The F.astern Highlands region has
the greatest proportion of stream length with
high riparian disturbance (29%, or 79,591 miles),
followed by the Plains and Lowlands (26%, or
62,504 miles) and the West (19%, or 29,570
miles). One of the striking findings of the WSA
is the widespread distribution of intermediate
levels of riparian disturbance; 47% of the nation's
stream length (314,052 miles) has intermediate
levels of riparian disturbance when compared to
reference condition, and similar percentages are
found in each of the three major regions.

   It is wotth noting that for the nation
and the three regions, the amount of stream
length with good riparian vegetative cover was
significantly greater than the  amount of stream
length with low levels of human disturbance
in the riparian zone. This finding warrants
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                                                               Chapter 2    Condition of the Nation's Streams
                                                                             Stream Length (mi)
                 National
                (lower 48)
                                     10
                                                                  50
                                                                         60
                                          20      30      40
                                         Percentage of Stream Miles
                            • Low  D Medium  H High  D Not Assessed
Figure 22. Riparian disturbance in U.S. streams (U.S. EPA/WSA). This indicator is based on field
observations of I I  different types of human influence (e.g., dams, pavement, pasture) and their proximity to
a stream in 22 riparian plots along the stream.
additional investigation, but suggests that land
managers and property owners are protecting and
maintaining healthy riparian vegetation buffers,
even along streams where disturbance from roads,
agriculture, and gra/ing is widespread.

Biological Stress ors
   Although most of the factors identified as
strcssors to streams and rivers are cither chemical
or physical, there are biological factors that also
create stress in wadeable streams.  Biological
                                                      assemblages can be stressed by the presence of
                                                      non-native species that can either prey on, or
                                                      compete with, native species. In many cases, non-
                                                      native species have been intentionally introduced
                                                      to a waterbody; for example, brown trout and
                                                      brook trout arc common inhabitants of streams in
                                                      the higher elevation areas of the West, where they
                                                      have been  stocked as game fish.

                                                        When non-native species become established in
                                                      either vertebrate or invertebrate assemblages,  their
                                                      presence conflicts with the definition of biological
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Chapter 2   Condition of the Nation's Streams
          Little Washita River, OK, in the Plains and Lowlands region (Photo courtesy of Monty
          Porter).
integrity that the CWA is designed to protect
(i.e., "having a species composition, diversity, and
functional organization comparable to that of the
natural habitat of the region"). Therefore, to the
extent that non-native species compete with and
potentially exclude native species, they might be
considered a threat to biological integrity. These
indicators were not included in the WSA, but
may be included in future assessments.


Ranking of Stressors

   A prerequisite to making policy and
management decisions is to understand the
relative magnitude or importance of potential
stressors. It is important to consider both the
prevalence of each stressor (i.e., what is its extent,
in miles of stream, and how does it compare to
other stressors) and the severity of each stressor
(i.e., how much influence does it have on
biological condition, and is its influence greater
or smaller than the influence of other stressors).
The WSA presents separate rankings of the
extent and the relative severity of stressors to the
nation's flowing waters. Ideally, both of these
factors (extent and effect) should be combined
into a single measure of relative importance.
EPA is pursuing methodologies for combining
the two rankings and will present them in future
assessments.
Extent of Stressors
   Figure 23 shows the WSA stressors ranked
according to the proportion of stream length that
is in poor condition. Results are presented for
the nation (top panel) and for each major region,
with the stressors ordered (in all panels) according
to their relative extent nationwide.
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   Figure 23 reveals that excess total nitrogen
is the most pervasive stressor for the nation,
although it is not the most pervasive in each
region. Approximately 32% of the nation's stream
length (213,394 miles) shows high  concentrations
of nitrogen compared  to reference conditions.
In the Plains and Lowlands region, nitrogen
is at high concentrations in 27% of stream
length (65,715 miles), whereas this proportion
        Chapter 2   Condition of the Nation's Streams


climbs to 42%  (1 17,285 miles) in the Eastern
Highlands region, hven in the West, where levels
of disturbance are generally lower than the other
major regions, excess total nitrogen is found
in 21% of the stream length (31,247 miles).
Phosphorus exhibits comparable  patterns to
nitrogen and is the second most-pervasive stressor
for the nation's stream length.
                                                                                  Stream Length (mi)
                   National
                  (lower 48)
                           213,394
                           207,355
                           171,118
                           167,092
                           130,928
                           129,748
                            19,889
                            14,763
                   Eastern
                  Highlands
                            117,284
                            117,730
                            79,591
                            77,381
                            22,797
                            48,640
                             3,593
                             9,396
                                                               27.
                                                             24.9%
                                                              25.8%
                                                               26.4%
                            65,715
                            60,324
                            62,504
                            63,958
                            89,638
                            62,881
                            12,113
                            4,603
Plains and
Lowlands
                                                         20.5%
                                                       18.5%
                                                      HI 9.4%
                                                      17.4%
                            31,247
                            28,174
                            29,570
                            26,522
                            18,748
                            18,596
                            4,009
                             762

                                                     20        30        40
                                                  Percentage of Stream Miles

                                   N = Nitrogen            1-sFH = In-stream Fish Habitat
                                   P = Phosphorus          RVC = Riparian Vegetative Cover
                                   RD = Riparian Disturbance   S = Salinity
                                   SS = Streambed Sediments   A = Acidification
Figure 23. Extent of stressors (i.e., proportion of stream length ranked in poorest category for each stressor)
(U.S. EPA/WSA).
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Chapter 2   Condition of the Nation's Streams
   The least-common stressors for the nation's
stream length are salinity and acidification. Only
3% (19,889 miles) and 2% (14,763 miles),
respectively, of the nation's stream length is in
poor condition for salinity and acidification levels.
Although these stressors are not present in large
portions of the nation's streams, they can have a
significant impact where they do occur.
   The extent of stressors measured in the WSA
varies across the three major regions. In the Plains
and Lowlands region, the stressor rated poor for
the greatest proportion of stream  length (37%, or
89,638 miles) is loss of in-stream  fish habitat.  In
the Eastern Highlands region, high total nitrogen
and total phosphorus concentrations were found
in more than 42% of the stream length (1 17,285
and 117,730 miles, respectively).  In the West,
no stressor is found to affect more than 21 % of
stream length (31,247 miles), although nitrogen,
phosphorus, and riparian disturbance are the
most widespread stressors  in this region as well.

Relative Risk of Stressors  to
Biological Condition
   This report borrows the concept of relative risk
from the medical field to address  the question of
severity of stressor effects.  We have all heard that
we run a greater risk of developing heart disease  if
we have high cholesterol levels. Often such results
are presented in terms of a relative-risk ratio (e.g.,
the risk of developing heart disease is 4 times
higher for a person with a total cholesterol level
greater than 300 mg than  for a person  with a total
cholesterol level of less than 150 mg).
   The relative-risk values for aquatic stressors
can be interpreted in the same way as the
cholesterol example. For each of the key stressors,
Figure 24 depicts how much more likely a stream
is to have poor biological condition if stream
length is in poor condition for a stressor or if high
ecncentrations of a stressor are present than if the
stream length is in good condition ror a stressor
or a stressor is found at low concentrations.
Because different aspects of the macroinvertcbrate
assemblage (i.e., biological  condition vs. taxa loss)
are expected to be  affected by different stressors,
the WSA calculates relative risk separately lor
each of the two biological condition indicators
(Macroinvertebrate Index and O/E Taxa Loss).

   A relative-risk value of 1 indicates that there
is no association between the stressor and the
biological indicator, whereas values greater than 1
suggest that the stressor poses a greater relative risk
to biological condition. The WSA also calculates
confidence intervals (Figure 24) for each relative
tisk ratio. When the confidence interval extending
above and below the ratio does not overlap the
value of  1, the relative risk estimate is statistically
significant.

   The relative risks shown in Figure 24 provide
an estimate of the  severity of each stressor's
effect on the macroinvertebrate community in
streams. Almost  all of the stressors evaluated
for the WSA were  associated with increased
risk for macroinvertcbrates. Evaluating relative
risk provides insight on which stressors might
be addressed to improve biological condition.
Excess nitrogen, phosphorus, and streambed
sediments stand out as having the most significant
impacts on biological condition based on both
the Macroinvertebrate Index  and O/E Taxa Loss
indicators. Findings show that streams with
relatively high concentrations of nutrients or excess
streambed sediments  are two to four times more
likely to  have poor macroinvertebrate condition.
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                                                                    Chapter 2   Condition of the Nation's Streams
                           Extent of Stressor
 Relative Risk to
Macroinvertebrate
   Condition
  Relative Risk
      O/E
   Taxa Loss
                      Percentage Stream Length in Most
                           Disturbed Condition
2      3      4
   Relative Risk
234
   Relative Risk
                    N = Nitrogen   RD = Riparian Disturbance  1-sFH = In-stream Fish Habitat   S = Salinity
                    P = Phosphorus SS = Streambed Sediments  RVC = Riparian Vegetative Cover A = Acidification

Figure 24. Extent of stressors and their relative risk to Macroinvertebrate Condition and O/E
Taxa Loss (U.S. EPA/WSA). This figure shows the association between a stressor and biological condition and
answers the question,"What is the increased likelihood of poor biological condition when stressor X is rated
in poor condition?" It is important to note that this figure treats each stressor independently and does not
account for the effects of combinations of stressors.
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Chapter 2    Condition of the Nation's Streams
   I here are differences in relative risk from
a geographic perspective. In general, the West
exhibits a higher relative risk for the majority
of" stressors than the Eastern Highlands and
the Plains and Lowlands regions. There are
also differences associated with the different
indicators of biological condition.  The O/F
Taxa Loss indicator has somewhat  higher relative
risk ratios for most of the stressors than the
Macroinvertcbrate Index. Additional analysis is
needed to further explore these differences.
   In this assessment of relative risk, it is
impossible to separate completely the effects
of the individual stressors that often occur
together. For example, streams with  high nitrogen
concentrations often exhibit high phosphorus
concentrations, and streams with high riparian
disturbance often have sediments far in excess of
expectations; however, the analysis presented in
Figure 24 treats the stressors as if they operate
independently.

Combining Extent and Relative
Risk
   The most comprehensive assessment of the
ranking of stressors comes from evaluating both
the extent (Figure 23) and relative risk (Figure 24)
results. Stressors that pose the greatest overall risk
to biological integrity will be those that are both
widespread (i.e., rank high in terms of the extent
of stream length in poor condition for a stressor
in Figure 23) and whose effects are potentially
severe (i.e., exhibit high relative risk ratios in
Figure 24). The WSA facilitates this combined
evaluation of stressor importance by including
side-by-side comparisons of the extent of stressors
and relative risk to macro in vertebrate condition
in Figure 24.

   An examination of nationwide results suggests
some common patterns for key stressors and
the two indicators of biological condition.  Total
nitrogen, total phosphorus, and excess streambed
sediments are stressors posing the greatest relative
risk nationally (relative risk greater than 2), and
they also occur in 25—32% of the nation's stream
length. This suggests that management decisions
aimed at reducing excess sediment, nitrogen,
and phosphorus loadings to streams could  have a
positive impact on macroinvertebrate biological
integrity and prevent further taxa loss across the
country.

   I ligh salinity in the West is strongly associated
with a poor Macroinvertebrate Index score
(relative risk = 2.5) and O/K Taxa Loss score
(relative risk > 3.1 or = 3.2); however,  the rarity of
this occurrence (salinity affects only 3% of stream
length in the West region)  suggests that excess
salinity is a local issue  requiring a locally targeted
management approach rather than a national or
regional effort.

   Relative risks for all stressors in the  West: region
are consistently larger than for the nation overall
or for the other two  regions, yet the extent of
streams  in poor condition for these stressors is
consistently lower in the West. This suggests that
although the stressors are not widespread in the
West, the region's streams are particularly sensitive
to a variety of disturbances.
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  Chapter 3
Wade able Streams Assessment
Ecoregion Results

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Chapter 3   Wadeable Streams Assessment Ecoregion Results
Wadeable  Streams

Assessment  Ecoregion

Results

   The WSA is designed to report on three
geographic scales: national, regional, and
ecoregional. Chapter 2 presented the national-
and regional-scale results, and this chapter will
focus on the results for the nine WSA ecoregions.

   Ecoregions are areas that contain similar
environmental characteristics, such as climate,
vegetation, soil type, and geology. EPA has
defined ecoregions at various scales, ranging from
coarse (Level I) ecoregions at the  continental scale
to fine (Levels III and IV) ecoregions that divide
states into smaller ecosystem units. Ecoregions arc-
designed to be used in environmental assessments,
for setting water quality and biological criteria,
and to set management goals for  non-point source
pollution.

   The nine WSA ecoregions are  aggregations of
the Level III ecoregions delineated by EPA for
the conterminous United States. This chapter
provides background information on physical
setting, biological setting, and human influence
for each of the WSA ecoregions and  describes
WSA results for the wadeable stream length
throughout each ecoregion. The WSA results
may not be extrapolated to an individual state or
stream within the ecoregion because the study
design was not intended to characterize stream
conditions at these finer scales. Note that a
number of states implement random i/,ed designs
at the state scale to characterize water quality
throughout their state, but these  characterizations
are not described in this WSA report.
    Manistee River, Ml, in the Upper Midwest
    ecoregion (Photo courtesy of the Great Lakes
    Environmental Center).
  The nine ecoregions encompass a variety of
habitats and land uses, and the least-disturbed
reference sites used to set benchmarks for good, fair,
and poor condition reflect that variability. For some
ecoregions, the variability among reference sites
is very small, while it is larger in others. During a
series of WSA workshops held around the country,
professional biologists examined the variability of
reference sites and implications to the benchmarks
used to characterize an ecoregion arid to compare
stream condition across ecoregions. These
benchmarks or thresholds were adjusted for those
ecoregions where there was a disturbance signal
associated with the variability among reference
sites. Additional details on the development oi~
benchmarks or thresholds for each of the indicators
can be found in the data analysis method available
in Chapter f and on the EPA Web site at http://
wvvw.epa.gov/owow/streamsurvey.
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                                                     Chapter 3   Wodeob/e Streams Assessment Ecoreg/on Results
   This report includes brief descriptions of the
WSA ccoregions. It should be noted that there
are many specific and unique features within each
ecoregion that are not fully captured in these brief
descriptions (see the  References section at the end
of this report  for more information). The nine
ecoregions displayed  in Figure 25 and defined in
this text are the following:
Northern Appalachians
Southern Appalachians
Coastal Plains
Upper Midwest
Temperate Plains
Southern Plains
Northern Plains
Western Mountains
Xeric.
       WSA Ecological Regions
  ^g| Northern Appalachians |   | Southern Plains
  I   I Southern Appalachians |   | Northern Plains
     Coastal Plains      H Western Mountains
  I   I Upper Midwest     I   I Xeric
  i   I Temporate Plains
Figure 25.  Ecoregions surveyed for the WSA (U.S. EPA/WSA).
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Chapter 3   Wodeob/e Streams Assessment Ecoreg/on Results
Northern Appalachians
Ecoregion

Physical Setting
  The Northern Appalachians ecoregion covers
all of rhe New England states, most of New
York, the northern half of Pennsylvania, and
northeastern Ohio. This ecoregion encompasses
New York's Adirondack and Catskill mountains
and Pennsylvania's mid-northern tier, including
the Allegheny National Forest. Major river
systems for the Northern Appalachians ecoregion
are the St.  Lawrence, Allegheny, Pcnobscot,
Connecticut, and Hudson rivers, and major
waterbodies include Lake Ontario, Lake Erie,
New York's Finger Lakes, and Lake Champlain.
The total stream length represented in the WSA
for the Northern Appalachians ecoregion is
97,913 wadeable stream miles.

  The topography of this ecoregion is generally
hilly, with  some intermixed plains and old
mountain  ranges. River channels in the glaciated
uplands of the northern parts of this ecoregion
have steep profiles and rocky beds, and flow
over glacial sediments. The climate is cold to
temperate, with mean annual temperatures
ranging from 39 to 48 °F. Annual precipitation
totals range from 35  to 60 inches. The land area
of Northern Appalachians ecoregion comprises
some 139,424 mi2 (4.6% of the United States),
with about 4,722 mi' (3-4%) of land under
federal ownership. Based on satellite images from
the 1992 National Land Cover Dataset (NLCD),
the distribution of land cover in this ecoregion is
69% forested and 17% planted/cultivated, with
the remaining 14% of the ecoregion comprised of
other types of land cover.
  Cedar Stream, NH, in the Northern Appalachians
  ecoregion (Photo courtesy of Colin Hill,TetraTech, Inc.)
Biological Setting
   Contemporary fish stocks are lower than at the
time of European contact, but the coastal rivers of
the Northern Appalachians ecoregion still have a
wide variety of anadromous fish, including shad,
alewife, salmon, and sturgeon.

Human Influence
   Early European settlers in 17th-century New
England removed beaver dams, allowing floods
to pass more quickly, thereby flushing sediment
and decreasing the diversity and availability of
riparian habitat. Forests were cleared to introduce
crops and pasture for grazing animals, and these
efforts  caused the erosion of sediments, increased
nutrients, and reduced riparian habitat. Roughly
96% of the original virgin forests of the eastern
and central states were gone by the 1920s.
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                                                  Chapter 3   Wadeable Streams /Assessment Ecoregion Results
   Smaller tributaries in this ecoregion were
often disrupted through splash damming — a
19th century practice of creating dam ponds
for collecting timber and then exploding the
dams to move timber downstream with the
resulting torrent of flood waters. These waters
earned flushed sediment anci wood downstream,
and these materials scoured many channels to
bedrock. Streams that were not splash dammed
currently have tens to hundreds of times more
naturally occurring woody debris and deeper
pools. During the 18th and early 19th centuries,
streams with once-abundant runs of anadromous
fish declined due to stream sedimentation,
clogging from sawmill discharges, and the effects
of dams. Increased human and animal waste
from  agricultural communities changed stream
nutrient chemistry. When agriculture moved west
and much of the ecoregion's eastern farmland
converted back into woodlands, sediment yields
declined in some areas.

   Today, major manufacturing, chemical,
steel,  and power production (e.g., coal, nuclear,
oil) occur in the large metropolitan areas
found around  New York City and the states of
Connecticut and Massachusetts. Many toxic
substances, including petroleum products,
organochlorines, polychlorinated biphenyls
(PCBs), and heavy metals, along with increased
nutrients such as nitrates and phosphates, are
the legacy of industrial  development. There are
currently 21 5 active, 6 proposed, and 45 former
Li PA Superfuncl National Priority List sites in the
Northern Appalachian ecoregion.

   It is also common for treated wastewater
effluent to account for much of the stream  flow
downstream from major urban areas in this
ecoregion.  treated wastewater can be a major
source of nitrate, ammonia, phosphorus, heavy
metals, volatile organic chemicals (VOCs), PCBs,
and other toxic compounds.
   'This ecoregion supports forestry; mining;
fishing; wood processing of pulp, paper, and
board; tourism; and agricultural activities, such as
dairy cattle farming, potato production, poultry
farming, and timber harvesting.
   The approximate population within the
Northern Appalachians ecoregion is 40,550,000,
representing approximately 14% of the total
population of the United States.

Summary ofWSA Findings
   A total of 85 WSA  sites were sampled during
the summer of 2004 to characterize the condition
of wadeable streams in the Northern Appalachians
ecoregion. An overview of the WSA survey results
for this ecoregion is shown in figure 26. 'These
results may not be extrapolated to accurately
assess the ecological condition of an individual
state or stream within  the ecoregion because the
study design was not intended to characterize
stream conditions at these finer scales.
   It should be noted that  about 27% of wadeable
stream length in the Northern Appalachians
ecoregion was nor assessed because small,
Isr-order streams in New Lingland were not
included in the sample frame. These streams
were excluded from the WSA due to a decision
to match an earlier New Lingland random design.
'The numbers cited below apply to the 73% of
wadeable stream length that was assessed in  the
Northern Appalachians ecoregion.
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Chapter 3   Wadeable Streams Assessment Ecoreg/on Results
                                                                        Streambed Sediments
                                                                                   H 28%
                                                                               14%
                                                                                   H 29%
                                                                                    29%
    Northern Appalachians Ecoregion
            97,913 miles

| Macroinvertebrate Index
      •113%
       HI 5% 	
                   45%
                            27%
0      20      40      60     80
         Percentage Stream Length
  For Macroinvertebrate Index:
  H Good n Fair S Poor  L~] Not Assessed
  For O/ETaxa Loss:
  H > 50% Taxa Loss   n 20-50% Taxa Loss
  D 10-20% Taxa Loss • < 10% Taxa Loss
  D Not Assessed
                                                                                         H 44%
                               iparian Vegetative Cover
                                       20%
                                       —H 27%
                                          26%
                                       -H 27%
20      40     60
    Percentage Stream Length
                                     H Low
                                     D Medium
                                     H High
                                     D Not Assessed
                                                                    100 0     20     40      <>0      80
                                                                                 Percentage Stream Length
                               H Good
                               D Fair
                               • Poor
                               n Not Assessed
Figure 26. WSA survey results for the Northern Appalachians ecoregion (U.S. EPA/WSA).  Bars show
the percentage of stream length within a condition class for a given indicator Lines with brackets represent
the width of the 95% confidence interval around the percent o'F stream length. Percents may not add up to 100
because of rounding.
   During a scries of WSA workshops conducted
to evaluate assessment results, professional
biologists working in the Northern Appalachians
ecoregion said that many least-disturbed reference
sites in this ecoregion are nearly tindisturbed
streams, with sparse human population in the
immediate watershed; therefore, the  reference
condition  for the ecoregion is of very high quality.

Biological  Condition
 • The findings of the Macroinvertebrate Index
   show that 45% of stream length in  the
   Northern Appalachians ecoregion is in poor
   condition, ] 5% is in intermediate or fair
   condition, and 13% is in good condition
   when compared to least-disturbed reference
   condition. As noted above, Ist-order streams,
   which are generally considered to be of high
                  quality in this ecoregion, were not included in
                  the WSA.
                • The O/ETaxa Loss results show that 50% of
                  stream length in the Northern Appalachians
                  ecoregion has lost 10% or more of the
                  macromvei tebratc taxa expected to occur, and
                  19% has lost more than 50% of taxa. These
                  results indicate that 23% of stream length has
                  retained 90% of the groups or classes of
                  organisms expected to occur based on least-
                  disturbed reference  condition.

               Indicators of Stress
                  Leading indicators of stress in the Northern
               Appalachians  ecoregion include total phosphorus,
               total nitrogen, streambed sediments, and riparian
               vegetative cover.
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                                              Chapter 3   Wadeable Streams Assessment Ecoregion Results
Approximately 45% of stream length in the
Northern Appalachians ecoregion has high
phosphorus concentrations, 16% has medium
phosphorus concentrations, and 12% has low
phosphorus concentrations based on least-
disturbed reference condition.
Similarly, approximately 45% of the
ecoregion's stream length has high nitrogen
concentrations, 10% has medium nitrogen
concentrations, and 1 8% has low nitrogen
concentrations based on least-disturbed
reference condition.
Riparian disturbance, or evidence of human
influence in the riparian zone, is at high levels
in 20% of stream length, at medium levels
in 34% of stream length, and at low levels in
19% of stream length.
Salinity is found at high levels in 1% of stream
length, at medium levels in 8% of stream
length, and at low levels in 64% of stream
length.
Streambcd sediments are rated poor  in 29% of
stream length in the Northern Appalachians
ecoregion, fair in 14%, and good in  28%.
In-stream fish habitat is in poor condition in
16% of stream length, fair in 13% of stream
length, and good in 44%.
Vegetative cover in the  riparian zone along
stream banks is in poor condition for 26% of
stream length, fair condition for 27% of stream
length, and good condition for 20% of stream
length.
Acidification, which is primarily associated with
acid rain in this ecoregion, is rated poor in 3%
of stream length.
           Stream channels in the glaciated uplands of the Northern Appalachians
           are characterized by steep profiles and rocky beds (Photo courtesy of
           Lauren Holbrook, IAN Image Library).
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Chapter 3   Wadeable Streams Assessment Ecoreg/on Results
Southern Appalachians
Ecoregion

Physical Setting
  The Southern Appalachians ecoreglon stretches
over 10 states, from northeastern Alabama to
central Pennsylvania, and includes the interior
highlands of the Ozark Plateau and the Ouachita
Mountains in Arkansas, Missouri, and Oklahoma.
  The land area of the Southern Appalachians
ecoregion covers about 321,900 mr (10.7%
of the United States), with about 42,210 mr
(13.1%) of land under federal ownership. Many
significant public lands, such as the Great Smoky
Mountains National Park, the George Washington
and Monongahcla national forests, and the
Shenandoah National Park, reside within this
ecoregion. The topography is mostly hills and low
mountains, with some wide valleys and irregular
plains. Piedmont areas are included within the
Southern Appalachians ecoregion.
  Rivers in this ecoregion flow mostly over
bedrock and other resistant rock types, with steep
channels and short meander lengths. Major rivers
such as the Susquehanna, James, and Potomac,
along with feeders into the Ohio and Mississippi
river systems, such as the Greenbrier River in
West Virginia, originate in this ecoregion. The
total stream length represented in the WSA for
the  Southern Appalachians ecoregion is 178,449
wadeable stream miles.

   This ecoregion's climate is considered
temperate wet.  and annual precipitation
totals average 40 to 80 inches. Mean annual
te:npcraturc ranges from 55 to 65 °h. Based
on satellite images in the 1992 NLGD, the
distribution oi land cover in this ecoregion is 68%
forested and 25% planned/cultivated, with the
remaining 7% in other types of land cover.
Biological Setting
   I nc Southern Appalachians ecoregion has
some of the greatest aquatic animal diversity of
any area in North America, especially for species
    Young Womans Creek,
    PA, in the Southern
    Appalachians
    ecoregion (Photo
    courtesy of the Great
    Lakes Environmental
    Center).
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                                                  Chapter 3   Wadeable Streams Assessment Ecoregion Results
(if amphibians, fishes, mollusks, aquatic insects,
and crayfishes. Salamanders, plants, and fungi
reach their highest North American diversity in
the Southern Appalachians ecorcgion; however,
some 18% of animal and plant species in the
ecoregion are threatened or endangered.

   Some areas in the Southern Appalachians
ecoregion are among the least-impacted pre-
settlcment vegetative cover in the United States,
such as the spruce-fir forests in the southern part
of the ecoregion. The Great Smoky Mountains
National Park and other national forests continue
to protect exceptional stands of old-growth forest
riparian ecosystems.
Human Influence
   The effects of habitat fragmentation, urbaniza-
tion, agriculture, channelization, diversion, and
impoundments on river systems have altered a
large amount of stream length in the Southern
Appalachians ecoregion. Placer mining, which
disrupts streambeds and increases a stream's
ability to transport fine sediments that influence
habitat and water quality downstream, began in
the Appalachians in the  1820s. In addition, some
800 mr were surface mined in the Appalachian
Highlands between  1930 and 1971, leading
to the acidification of streams and reduction
of aquatic diversity.  Placer mining and surface
mining operations have introduced many toxic
contaminants to river systems in  the Southern
Appalachians ecoregion, including arsenic,
antimony, copper, chromium, cadmium,
nickel, lead, selenium, silver, and zinc. There
are 224 active, 5 proposed, and 46 deleted  EPA
Superfund National Priority List sites in this
ecoregion.
   Economic activities in the Southern
Appalachians ecoregion include forestry,
coal mining, and some local agriculture and
tourism industries. Petroleum and natural gas
extraction are prevalent along the coal belt,
and the ecoregion supports coal, bauxite, zinc,
copper, and chromium mining activities. Utility
industries include hydro-power in the Tennessee
Valley and  numerous coal-fired plants throughout
the ecoregion. Significant agricultural activities
are alfalfa production in Pennsylvania, with apple
and cattle production occurring throughout the
ecoregion. Wood processing and pulp, paper, and
board production arc also prevalent.

   Approximately 50,208,000 people live in the
Southern Appalachians ecoregion, representing
approximately 17% of the total population of the
United States.

Summary ofWSA Findings
   A total of 1 84 random sites were sampled
during the  summer of 2004 to characterize the
condition of wadeable streams in the Southern
Appalachians ecoregion. An overview of the WSA
survey results for the ecoregion is shown in Figure
27. These results may not be extrapolated to an
individual state or stream within the ecoregion
because the study design was not intended to
characterize stream conditions at these finer scales.

   During a series of WSA workshops conducted
to evaluate assessment results, professional
biologists working  in the Southern Appalachians
ecorcgion said that the least-disturbed reference
streams in the ecoregion represent varying degrees
of human influence. Although some reference
streams are in remote areas, others are intricately
linked with road systems in narrow floodplains.
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Chapter 3   Wadeable Streams Assessment Ecoreg/on Results
    Southern Appalachians Ecoregion
            178,449 miles

I Macroinvertebrate Index
         I 21%
          I 24%	
                      55%
 O/E Taxa Loss
          36%
     20     40     60
       Percentage Stream Length
For Macroinvertebrate Index:
• Good D Fair  BO Poor D Not Assessed
For O/E Taxa Loss:
B > 50% Taxa Loss  D 20-50% Taxa Loss
D  10-20% Taxa Loss • < 10% Taxa Loss
  Not Assessed
                                                                         Streambed Sediments
                                                                                       H 41 %
                                                                                      32%
                                                                                    27%
                                                                                               -H 62%
                                          20      40     60
                                             Percentage Stream L.ength
                                     H Low
                                     G Medium
                                     I] High
                                     D Not Assessed
             100  0      20      40      60     £
                          Percentage Stream Length
                 • Good
                 D Fair
                 ES Poor
                 D Noi: Assessed
  i—i iNot /Assessed
Figure  27. WSA survey results for the Southern Appalachians ecoregion (U.S. EPA/WSA).  Bars
show the percentage of stream length within a condition class 'cor a given indicator.  Lines with brackets
represent the width of the 95% confidence interval around the percent of stream length. Percents may not
add up to 100 because of rounding.
Biological Condition
 • The Macroinvertebrate Index shows that 55%
   of stream length in the Southern Appalachians
   ecoregion is in poor condition, 24% is in
   fair or intermediate condition, and 2] % is in
   good condition compared to least-disturbed
   reference condition.
 • The O/E Taxa Loss results show that 65% of
   stream length in the Southern Appalachians
   ecoregion has lost 10% or more of the
   macroinvertebrate taxa that are expected to
   occur, and 16% has lost more than 50% of
   taxa. These results also indicate that 30% of
   stream length has retained 90% of the groups
   or classes of organisms expected  to occur based
   on least-disturbed reference condition.
Indicators of Stress
   Leading indicators of stress in the Southern
Appalachians ecoregion include total nitrogen,
total phosphorus, riparian disturbance, and
streambed sediments.
 " Forty-one percent of stream length in the
   Southern Appalachians ecoregion has high
   phosphorus concentrations, 1 5% has medium
   phosphorus concentrations, and 44% has low
   phosphorus concentrations based on least-
   disturbed reference condition.
 " Nitrogen concentrations in the ecoregion
   are high in 41% of stream length, medium
   in 20% of stream length, and low in 39%
   of stream length based on least-disturbed
   reference condition.
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                                                 Chapter 3   Wadeable Streams Assessment Ecoregion Results
  ' Riparian disturbance, or evidence of human
   influence in the riparian zone, is at high levels
   in 33% of stream length, at medium levels
   in 44% of stream length, and at low levels in
   23% of stream length.
  • Salinity is found at high levels in only 2% of
   stream length, at medium levels in 1 1% of
   stream length, and at low levels in 87% of
   stream length.
  • Streambed sediments are rated poor in 27%
   of stream length in the Southern Appalachians
   ecoregion,  fair in 32%, and good in 41%.
  • In-stream fish habitat is in poor condition in
   4% of stream length, fair in 34% of stream
   length, and good in 62%.
  • Vegetative cover in the riparian zone along
   Southern Appalachian stream banks  is in poor
   condition in 13% of stream length, fair in
   33% of stream length, and good in 54%  of
   stream length.
  • Acidification, which is primarily associated
   with acidic deposition and acid mine drainage
   in this ecoregion, is rated poot in 3% of stream
   length.

Coastal  Plains Ecoregion

Physical Setting
   The Coastal Plains ecoregion covers the
Mississippi Delta and Gulf Coast, north along the
Mississippi River to the Ohio River, all of Florida
and eastern Texas, and the Atlantic seaboard from
Florida to New Jersey. The total land area of this
ecoregion is about 395,000 mi2 (13.2% of the
United States), with 25,890 mi2 (6.6%) of land
under federal ownership. River systems lying
within or intersecting the Coastal Plains ecoregion
are the Mississippi, Suwannee, Savannah,
Roanoke, Potomac, Delaware, Susquehanna,
James, Sabinc, Brazos, and Cuadalupe rivers.

   Rivers in the Coastal Plains meander broadly
across flat plains created by thousands of years
of river deposition and form complex wetland
topographies with levees, backswamps, and oxbow
lakes. Rivers typically drain densely vegetated
catchment areas, while well-developed soils and
less intensive rains and subsurface flows keep
suspended sediment levels in the rivers relatively
low. The Mississippi River carries large loads
of sediments from dry lands in the central and
western  portion of the drainage. The total stream
length represented in the WSA for the Coastal
Plains ecoregion is 72,130 wadeable stream miles.
   Sandy Creek, LA, in the Coastal Plains
   ecoregion (Photo courtesy of the Great Lakes
   Environmental Center).
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Chapter 3   Wadeable Streams Assessment Ecoregion Results
   The Coastal Plains ecoregion contains about
one-third of all remaining U.S. wetlands, more
than half of U.S. forested wetlands, and the
largest aggregate area of U.S. riparian habitat.
i'he topography of the  area is mostly flat plains,
barrier islands, numerous wetlands, and about
50 important estuarine systems that lie along the
coastal margins. The climate of this ecoregion is
considered temperate wet to subtropical in the
south, with average  annual temperatures ranging
from 50 to 80 °F and annual precipitation
ranging from 30 to 79 inches. Based on satellite
images in the 1992 NLCD, the distribution of
land cover in this ecoregion is 39% forested,  30%
planted/cultivated, and 16% wetlands, with the
remaining  15% of the ecoregion comprised of
other types of land cover.
Human Influence
Biological Setting
   River habitats in the Coastal Plains ecoregion
have tremendous species richness and the
highest number of endemic species of aquatic
organisms in North America. Abundant fish,
crayfish, mollusk, aquatic insect, and other
species include such unique species as paddlefish,
catostomid suckers, American alligator, and giant
aquatic salamanders;  however,  it is estimated
that some 1 8% of the aquatic species in this
ecoregion are threatened or endangered. I he
Coastal Plains ecoregion includes the Florida
Everglades, which contains temperate and
tropical plant communities and a rich variety of
bird and wildlife species; however, because it is a
unique aquatic ecosystem, the  Everglades is not
represented  in the WSA.
   Historically, the Coastal Plains ecoregion had
extensive bottomlands that flooded for several
months; these areas are now widely channelized
and confined by levees. Damming, impounding,
and channelization in almost all major rivers
have altered the rate and timing of water flow,
as well as the productivity of riparian habitats.
Pollution from acid mine drainage, urban runoff,
air pollution, sedimentation, and recreation, as
we'll as the introduction of non-indigenous fishes
ard aquatic plants, have also affected riparian
habitats and native aquatic fauna. There arc
currently 275 active,  1.3 proposed, and 77 deleted
EPA Supcrfund National Priority List sites in the
Coastal Plains ecoregion.

   The ecoregion's economy is varied and includes
many activities. Agriculture in this ecoregion
includes citrus,  peanut, sugar cane, tobacco,
cattle, poultry, cotton, com, rice, vegetable,
and stone rruit production. Industries include
pulp, paper, board, and board wood processing;
aluminum production; salt, sulfur, bauxite,
and phosphate mining; and chemical and
plastics production. The Coastal Plains contain
approximately 40% of U.S. petrochemical
refinery capacity, much of which is located
offshore in  the Gulf of Mexico.

   This ecoregion also includes many large-
coastal cities, which contribute to a population of
approximately 56,168,000, the largest population
of all the WSA ecoregions, representing
approximately 19% of the population of the
United States.
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                                                     Chapter 3   Wadeable Streams Assessment Ecoregion Results
Summary  ofWSA Findings
   A total of 83 random sites were sampled during
the summer of 2004 to characterize the condition
of wadeable streams in the Coastal Plains
ecoregion. An overview of the WSA survey results
for this ecoregion is shown in  Figure 28. I hcsc
results may not be extrapolated to an  individual
state or stream within the ecoregion because the
study design was not intended to charactcn/e
stream conditions at these finer scales.
   During a series of WSA workshops
conducted to evaluate assessment results,
professional biologists working in the Coastal
Plains ecoregion said that the high prevalence
of human population centers, agriculture,
and industry makes it difficult to find truly
undisturbed streams in this ecoregion; therefore,
the ecoregion's least-disturbed reference sites are
influenced to some degree by human activities.
                                                                                                   64%
        Coastal Plains Ecoregion
            72,130 miles
 Macroinvertebrate Index
                I 36%
            \ 23%
               	H 39%
                    12%
           38%
0      20      40      60
j         Percentage Stream Length
I  For Macroinvertcbrate Index:
I  • Good n Fair  H Poor L7] Not Assessed
  For O/ETaxa Loss:
  B > 50% Taxa Loss   D 20-50% Taxa Loss
  D  10-20% Taxa Loss • < 10% Taxa Loss
  D Not Assessed
  20      40      60
      Percentage Stream Length

Low
Medium
High
Not Assessed
                      20     40     60
                          Percentage Stream Length
                 | Good
                 D Fair
                 H Poor
                 D Not Assessed
Figure 28. WSA survey results for the Coastal Plains ecoregion (U.S. EPA/WSA).  Bars show the
percentage of stream length within a condition class for a given indicator. Lines with brackets represent
the width of the 95% confidence interval around the percent of stream length. Percents may not add up to
100 because of rounding.
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Chapter 3   Wadeable Streams Assessment Ecoregion Results
Biological Condition
 • The Macroinvertebratc Index reveals char
   39% of stream length in the Coastal Plains
   ecoregion is in poor condition, 23% is in
   fair or intermediate condition, and 36% is in
   good condition compared to least-disturbed
   reference condition. No data were available to
   evaluate 2% of the ecoregion's stream length.
 • The O/E Taxa Loss results show that 65% of
   stream length in the Coastal Plains ecoregion
   has lost 10% ot mote of the macroinvertebrate
   taxa that ate expected to occur, and 15% has
   lost more than 50% of taxa. These results
   also indicate that 32% of stream length has
   tetained 90% of the groups or classes of
   organisms expected to occur based on least-
   disturbed reference condition.

Indicators of Stress
   Leading indicators of stress in the Coastal
Plains ecoregion include total phosphorus, m-
stream fish habitat, riparian vegetative cover, and
streambed sediments.
 • Twenty-nine percent of stream length in the
   Coastal Plains ecoregion has high  phosphorus
   concentrations, 1.3% has medium phosphorus
   concentrations, and 58% has low  phosphorus
   concentrations based on least-disturbed
   reference condition.
 • Ten percent of the ecoregion's stream length
   has high  nitrogen concentrations,  18% has
   medium  nitrogen concentrations,  and 72%
   has low nitrogen concentrations based on
   least-disturbed reference condition.
Riparian disturbance, or evidence of human
influence in the riparian zone, is at high levels
in 20% of stream length, at medium levels
in 50% of stream length, and at low levels in
30% of stream length.
Salinity is found at high or medium levels in
5% of stream length, with the remaining 95%
of stream length showing low levels for this
indicator.
Streambed  sediments  are rated poor in 22% of
stream length in the Coastal Plains ecoregion,
fair in 11% of stream length, and good in
64% of stream length based  on least-disturbed
reference condition; no data were available to
assess the remaining 3% of stream length.
In-stream fish habitat is in poor condition in
41% of stream length, fair in 13% of stream
length, and good in 46% of stream length,
based on least-disturbed reference condition.
Vegetative cover in the riparian zone along
stream banks is in poor condition for 24%
of stream length, fair condition for 24% of
stream length, and good condition in the
remaining  52% of stream length based on
least-disturbed reference condition.
In this ecoregion, the ANC is low enough to
result in episodic acidification during rainfall
in 6% of stream length. Another 5% of stream
length has  naturally lower pH.
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                                                Chapter 3   Wadeable Streams Assessment Ecoregion Results
Upper Midwest Ecoregion

Physical Setting
   The Upper Midwest ecoregion covers most
of the northern half and southeastern part of
Minnesota, two-thirds of Wisconsin, and almost
all of Michigan. The land area of the Upper
Midwest ecoregion comprises some  160,374 mr
(5.3% of the United States). The river systems
in this ecoregion empty into portions of the
Great Lakes regional watershed and  the upper
Mississippi River watershed. Major river systems
include the upper Mississippi River  in Minnesota
and Wisconsin; the Wisconsin, Chippewa, and
St. Croix rivers in Wisconsin; and the Menommee
and Escanaba rivers in Michigan. Streams in
the Upper Midwest ecoregion  typically drain
relatively small catchments and empty directly
into the Great Lakes or upper Mississippi River.
These streams generally have steep gradients, but
their topography and soils tend to slow runoff
and sustain flow throughout the year.

   The total stream length represented in the
WSA for the Upper Midwest ecoregion is 36,547
wadeable stream miles. Sandy soils dominate these
waterbodies, with relatively high water quality in
streams supporting cold-water fish communities.
Important waterbodies in this ecoregion  include
the Upper Mississippi River system and Lakes
Superior, Michigan, Huron, and Eric.

   The glaciated terrain of this ecoregion typically
consists of plains with some hill formations.
Numerous lakes,  rivers, and wetlands predominate
in most areas. The climate is characterized by
cold winters and relatively short, warm summers,
with mean annual temperatures ranging from
34 to 54 °F and annual precipitation in the
20- to 47-inch  range. Much of the land in this
ecoregion is covered by national and state forests,
  Raisin River, Ml, in the Upper Midwest
  ecoregion (Photo courtesy of the Great Lakes
  Environmental Center).

and federal lands account tor 1 5.5% of the area
(roughly 25,000 mr). Based on satellite images in
the 1992 NLCD, the distribution of land cover
in this ecoregion is  40% forested, 34% planted/
cultivated, and 17% wetlands, with the remaining
9% of the ecoregion comprised of other types of
land cover.
Biological Setting
   Vegetative cover for the Upper Midwest
ecoregion is mixed boreal woodland, mixed
oak-hickory associations, and conifers, as well as
bog and moss barrens. The Great Lakes aquatic
ecosystems are subject to increasing intrusion by
invasive animal and plant species introduced by
ocean shipping. These species include the zebra
mussel, the round goby, the river ruffe, the spiny
water flea, and Eurasian watermilfoil.
Human Influence
  The Upper Great Lakes portion of the Upper
Midwest ecoregion was entirely forested in
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Chapter 3   Wadeable Streams Assessment Ecoregion Results
pre-colonial times. Virtually all of the virgin forest
was cleared in the 19th and early 20th centuries,
and streams and rivers were greatly affected by
the logging industry. The upper Mississippi River
portion of the Upper Midwest ecoregion was also
heavily influenced by logging and agriculture.

   Major manufacturing, chemical, steel, and
power production (e.g., coal, nuclear, oil) occur in
the large metropolitan areas found in the Upper
Midwest ecoregion. Other key economic activities
are forestry, mining, and tourism. Agriculture
includes dairy production, grain crops in the
western areas, fruit production around the Great
Lakes, and  hay and cattle farming throughout
the ecoregion. Pulp, paper, and board wood
processing are prevalent throughout  the northern
parts of the ecoregion. The area includes the
shipping ports at Duluth, MN, and  Superior, WI,
as well as cities like Marquette, MI, and Hibbing,
MN, which were built up along with the mining
industry. The Upper Peninsula of Michigan lies
entirely within the Upper Midwesr ecoregion,
as does Minnesota's Mesabi Range, the largest
U.S. iron ore deposit. This area is subject to the
environmental effects of mining operations. There
are currently 112 active, 1  proposed, and 12
deleted EPA Superfund National Priority List sites
in this ecoregion.

   The approximate population of this area is
15,854,000, representing approximately 5% of
the population of the United States.

Summary  ofWSA Findings
   A total of 56 random sites were sampled in the
Upper Midwest ecoregion during the summer of
2004 to characterize the condition of its wadeable
streams. An overview of the WSA survey results
for the Upper Midwest ecoregion is  shown  in
Figure 29. These results may not be  extrapolated
to an individual state or stream within the
ecoregion because the study design was not
inrended to characterize stream conditions at
these finer scales.

  During a series of WSA workshops conducted
to evaluate assessment results, professional
biologists working in the Upper Midwest
ecoregion said that some of the ecoregion's least-
disturbed streams that serve as a benchmark for
reference condition are influenced by some form
of human activity or land use; however, most
of the least-disturbed reference sites are streams
in relatively undisturbed areas in the northern
portion of the ecoregion.

Biological Condition
 • The Macroinvertcbrate Index reveals that
   39% of stream length in the Upper Midwest
   ecoregion is in poor condition, 31% is in
   fair condition, and 28% is in good  condition
   based on least-disturbed reference condition.
 •  The O/LTaxa Loss results show that 54% of
   stream length in the Upper Midwest ecoregion
   has lost 10% or more of the  macroinvertebrate
   taxa that are expected to occur, and 5% has
   lost more  than 50% of  taxa. These results
   also indicate that 45% of stream length has
   retained at least 90% of the groups or classes
   of organisms expected to  occur based on least-
   disturbed  reference condition.

Indicators of Stress
  Leading indicators of stress in the Upper
Midwest ecoregion include total phosphorus, total
nitrogen, strcambed sediments,  and in-stream fish
habitat.
 • Thirty-eight percent of stream  length in
   the Upper Midwest ecoregion has high
   phosphorus concentrations,  18% has medium
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                                                    Chapter 3   Wodeoble Streams Assessment Ecoregion Results
       Upper Midwest Ecoregion
             36,547 miles
   croinvertebrate Index
              28%
              131%
 O/ETaxa Loss
Ml    3I%
                                                                         Streambed Sediments
                                                                                             50%
                                       69%
0      20      40      60
         Percentage Stream Length
  For Macroinvertebratc Index:
  • Good D Fail-  H Poor D Not Assessed
  For O/ETaxa Loss:
  • > 50% Taxa Loss   D 20-50% Taxa Loss
  D 10-20% Taxa Loss  • < 10% Taxa Loss
  D Not Assessed
  20      40      60
      Percentage Stream Length

Low
Medium
High
Not Assessed
                  20      40      60      80     100
                      Percentage Stream Length
              B Good
              D Fair
              m Poor
              n Not Assessed
Figure 29. WSA survey results for the Upper Midwest ecoregion (U.S. EPA/WSA). Bars show the
percentage of stream length within a condition class for a given indicator. Lines with brackets represent the
width of the 95% confidence interval around the percent of stream length.  Percents may not add up to 100
because of rounding.
   phosphorus concentrations, and 42% has low
   phosphorus concentrations based on least-
   disturbed reference condition.
 •  Iwcnty-one percent of the ecoregion's stream
   length has high nitrogen concentrations,
   30% of stream length has  medium nitrogen
   concentrations, and 48% of stream length has
   low nitrogen concentrations based on least-
   disturbed reference condition.
 • Riparian disturbance, or evidence of human
   influence in the riparian /.one, is at high levels
   in 6% of stream length, at medium levels in
   45% of stream length, and at low levels in
   49% of stream length.
 • Salinity is found at medium levels in 22%
   of stream length and at low levels in 77% of
   stream length.  None oi the steam length of the
Upper Midwest ecoregion showed high levels
for this indicator.
Streambed sediments are rated poor in 50% of
stream length, fair in 11%, and good  in 37%;
data for this indicator were not available for
2% of stream  length.
In-stream fish habitat  is  in poor condition in
17% of stream leneth, fair m 69% of  stream
                  O
length, and good in 14% of stream length
based on least-disturbed reference condition.
Vegetative cover in the riparian /one along
stream banks  is in poor condition in 13% of
stream length, fair condition in 38% of stream
length, and in good condition in  44% of
stream length.
The effects of acidification are not noted for
the Upper Midwest ecoregion.
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Chapter 3   Wodeob/e Streams Assessment Ecoreg/on Results
Temperate Plains  Ecoregion

Physical Setting
  1 he Temperate Plains ecoregion includes the
open farmlands of Iowa; the eastern Dakotas;
western Minnesota; portions of Missouri, Kansas,
and Nebraska;  and the flat farmlands of western
Ohio, central Indiana, Illinois, and southeastern
Wisconsin. The area of this ecoregion covers some
342,200 mi- (11.4% of the United States), with
approximately  7,900 mi: (2.3%) of land under
federal ownership. The ecoregion's terrain consists
of smooth plains and numerous small lakes and
wetlands. The climate is temperate, with fairly
cold winters; hot, humid summers; and mean
temperatures ranging from 36 to 55 °R Annual
precipitation in the Temperate Plains ecoregion
ranges from  16 to 43 inches.

  Many of the rivers in this ecoregion drain
into the Upper Mississippi and Ohio regional
watersheds, and a few systems empty into the
Great Lakes watershed near Toledo, OH; Saginaw,
MI; Detroit, MI; and southeastern Wisconsin.
Rivers are either supplied by snowmclt or
groundwater. Rivers in the tall grass prairie start
from prairie potholes and springs and are likely
to be ephemeral (flowing for a short time after
snowmelt or rainfall). The prairie rivers carry
large volumes of fine sediments and tend to be
turbid, wide, and shallow. The total stream length
represented in  the WSA for  the Temperate Plains
ecoregion is  100,879 wadeable stream miles.
Based on satellite images in the 1992 NLCD, the
distribution  of land cover in this ecoregion is 9%
forested and 76% planted/cultivated, with the
remaining 15% of the ecoregion comprised of
other types of land cover.
    Grey Horse Creek, OK, in the Temperate Plains
    ecoregion (Photo courtesy of Monty Porter).
Biological Setting
  Vegetation i:or the Temperate Plains ecoregion
consists primarily of oak, hickory, elm, ash, beech,
and maple, with increasing amounts of prairie
grasses to the west.  Rivers have rich fish fauna
with many species,  including minnows, darters,
killifishes, catfishes, suckers, sunfishes, and black
bass. Few species are endemic to the ecoregion.

Human Influence
  Pre-settlement vegetation of the area was
prairie grass and aspen parkland, but is now
comprised of about 75% arable cultivated lands.
This ecoregion is rich in agricultural production,
including held crops such as corn, wheat,
alfalfa, soybeans, flaxseed, and rye, along with
vegetable crops such as peanuts and tomatoes.
Hog and cattle production and processing are
also prevalent. Crops and grazing have reduced
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                                                  Chapter 3   Wadeable Streams Assessment Ecoreg/on Results
natural riparian vegetation cover, increased
sediment yield, and introduced pesticides and
herbicides into the watershed.  Conservation
tillage — a reduced-cultivation method — has
been implemented in about 50% of crop fields
in the Maumee River Basin and in northwestern
Ohio tributaries draining to Lake Erie. USGS
findings from 1993-1998 in these rivers
showed significant decreases in the amounts of
suspended sediment. Rivers in the Temperate
Plains ecoregion also tend to have high nitrogen
concentrations due to nutrients from agriculture
and from fertilizer applied to lawns and golf
courses in urban areas.  In Illinois, where land is
intensively developed through  urbanization and
agriculture, more than  25% of all sizable streams
have been channelized, and almost every stream
in the state has at least  one clam.

   Coal mining, petroleum and natural gas
production, and zinc and lead  mining occur
across the Temperate Plains ecoregion. There are
very active areas of manufacturing, steel produc-
tion, and chemical production in the ecorcgion's
urban centers, with especially high concentrations
near Detroit, MI, and the industrial belt from
Gary, IN, to Chicago, IL, and  Milwaukee, WI.
Industrial activities in these large urban centers
have contributed sewage, toxic compounds, and
silt to river systems. Heavy metals,
organochlorines, and PCBs are especially
prevalent and persistent river contaminants found
in industrial areas; however, many rivers have
improved from their worst state in the 1960s.
There are currently 133 active, 17 proposed, and
44 deleted EPA Superfund National Priority List
sites in the Temperate Plains ecoregion.

   The approximate population of this ecoregion
is 38,399,000, representing approximately 13%
of the U.S. population.
Summary ofWSA  Findings
   A total of 132 random sites were sampled
during the summer of 2004  to characterize the
condition of wadeable streams throughout the
Temperate Plains ecoregion.  An overview of the
WSA survey results for the Temperate Plains
ecoregion is shown in Figure 30. These results
may not be extrapolated to an individual state or
stream within the ecoregion  because the study
design was not intended to characterize stream
conditions at these finer scales.
   During a series of WSA workshops conducted
to evaluate assessment results, professional
biologists working in the lemperate Plains
ecoregion said  that it is hard to find high-quality
reference sites in the ecoregion because even
the least-disturbed streams are influenced by a
long history of land use. Extensive agriculture
and development have influenced virtually all
waterbodies in this ecoregion.

Biological Condition
 • The Macroinvertebrate Index reveals that
   37% of stream length in the Temperate Plains
   ecoregion is in poor condition, 36% is in
   fair condition, and 26% is in  good condition
   compared to least-disturbed reference
   condition.
 • The O/E Taxa Eoss results show that 39%
   of stream length in the Temperate Plains
   ecoregion has lost 10% or more of the
   macromvertebrate taxa that are expected to
   occur, and 10% has lost more than 50% of
   taxa. These results also indicate that 58% of
   stream length has retained 90% of the groups
   or classes of organisms expected to occur based
   on least-disturbed reference condition.
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Chapter 3   Wadeable Streams Assessment Ecoregion Results
                                                                         Streambed Sediments
                                                                                                   67%
                                                                            ream Fish Habitat
                                                                                  •
                                                                                  19%
Temperate Plains Ecoregion
      100,879 miles
 Macroinvertebrate Index
             26%
                36%
                37%
                                 arian Disturbance
                                3%
                                                                           rian Vegetative Cover
                                                                              H 17%
 O/E Taxa Loss
  M
  ffil  17%   12%
0     20     40      60
         Percentage Stream Length
  For Macroinvertebrate Index:
  • Good D Pair H Poor  D Not Assessed
                                                                        20      40      60      30
                                                                            Percentage Stream Length
                                        Low
                                        Medium
                                      E3 High
                                      D Not Assessed
                                                                      Gooc
                                                                    D Fair
                                                                    El Poor
                                                                    D Not Assessed
For O/E Taxa Loss:
FJ > 50% Taxa Loss  D 20-50% Taxa Loss
D  10-20% Taxa Loss • < 10% Taxa Loss
Figure 30. WSA survey results for the Temperate Plains ecoregion (U.S. EPA/WSA).  Eiars show the
percentage of stream length within a condition class for a given indicator. Lines with brackets represent the
width of the 95% confidence interval around the percent of stream length. Percents may not add up to 100
because of rounding.
Indicators of Stress
   Leading indicators of stress in the Temperate
Plains ecoregion include total nitrogen, riparian
disturbance, in-strearn fish habitat, and riparian
vegetative cover.

  • Approximately 12% of stream length in the
   Temperate Plains ecoregion has high
   phosphorus concentrations,  13% has medium
   phosphorus concentrations, and 74% has low
   phosphorus concentrations based on least-
   disturbed reference condition.
  • Approximately 41% of the ecoregion's stream
   length has high nitrogen concentrations, 17%
   has medium nitrogen concentrations, and
   41% has low nitrogen  concentrations based on
   least-disturbed reference condition.
                                                    • Riparian disturbance for this ecoregion is at
                                                      high levels in approximately 38% of stream
                                                      length, at medium levels in 58% of stream
                                                      length, and at low levels in 3% of stream
                                                      length.
                                                    • Salinity is found at high levels m 2% of stream
                                                      length, at medium levels in 13% of stream
                                                      length, and at low levels in 84% of stream
                                                      length.
                                                    • Excess streambed sediments affect streams in
                                                      the Temperate Plains ecoregion  to a lesser
                                                      extent than other physical stressors.  Streambed
                                                      sediments are rated poor in 20% of stream
                                                      length in this ecoregion,  fair  in  12%, and good
                                                      in 67% based on least-disturbed reference
                                                      condition.
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                                                 Chapter 3   Wadeable Streams Assessment Ecoregion Results
  * In-stream fish habitat is in poor condition in
   39% of stream length, fair in 19% of stream
   length, and good in 41% of stream length
   based on least-disturbed reference condition.
  • Vegetative cover in the riparian /one along
   stream banks is in poor condition for 26%
   of stream length, fair condition for 17% of
   stream length,  and good condition for 53% of
   stream length.
  • The effects of acidification are not noted  for
   the Temperate  Plains ecoregion.

Southern Plains Ecoregion

Physical Setting
   The Southern Plains ecoregion covers
approximately 405,000 mr (13.5% of the
United States) and includes central and  northern
Texas; most  of western Kansas and Oklahoma;
and portions of Nebraska, Colorado, and New
Mexico. I he retrain is a mix of smooth and
irregular plains interspersed with tablelands
and low hills. The Arkansas,  Platte, White,
Red, and Rio Grande rivers flow through this
ecoregion, and most of the great Ogallala aquifer
lies underneath this ecoregion.  The total stream
length represented  in the WSA for the Southern
Plains ecoregion is  19,263 wadeable stream miles.

   Most of the land use is arable and arable
with gra/ing, with desert or semi-arid  grazing
land in the south.  Based on satellite images
in the  1992  NI.CD, the distribution of land
cover in this ecoregion is 45% grassland, 32%
planted/cultivated, and 14% shrubland, with
the remaining 9% of the ecoregion comprised of
other types of land cover. Federal land ownership
in this ecoregion totals about 1 1,980 mr or
approximately 3%) of the total, the lowest share
of all WSA aggregate ecoregions.  The climate is
dry temperate, with the mean annual temperature
ranging from 45 to 79 °F. Annual precipitation
for the ecoregion is between 10 and 30 inches.
Biological Setting
  Vegetative cover in the northern portion of
this ecoregion is mainly short prairie grasses such
as buffalo grass, while in the southern portion,
grasslands with mesquite, juniper, and oak woody
vegetation are common. Coastal vegetation in the
southern Plains ecoregion is typically more salt-
tolerant in nature.
   Commission Creek, OK, in the Southern Plains
   ecoregion (Photo courtesy of Monty Porter).
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Chapter 3  Wadeable Streams Assessment Ecoregion Results

Human Influence
   The Great Prairie grasslands, which once
covered much of the Southern Plains ecoregion,
are the most altered and endangered large
ecosystem in the United States. About 90% of
the original tall grass prairie was replaced by
other vegetation or land uses.  Agriculture is an
important economic activity in this ecoregion and
includes sorghum, wheat, corn, sunflower, bean,
and cotton production. Livestock production
and processing is prevalent, especially goats,
sheep, and cattle. The eeoregion contains a
sizable portion of U.S. petroleum and natural
gas production in Oklahoma,  Kansas, and Texas.
Electricity in this ecoregion is generated almost
exclusively with gas-fired power plants. Some
uranium and zinc mining is found in Oklahoma
and the Texas panhandle. There are currently
                                    Phosphorus
                                                        39 active, 5 proposed, and 14 deleted EPA
                                                        Superfund National Priority List sites in this
                                                        ecoregion.

                                                           The approximate population in this ecoregion
                                                        is 18,222,000, representing roughly 6% of the
                                                        population of the United States.

                                                        Summary ofWSA  Findings
                                                           A total of 49 random sites were sampled during
                                                        the summer of 2004 to characterize the condition
                                                        of  wadeable streams throughout the Southern
                                                        Plains ecoregion. An overview of the WSA survey
                                                        results for the ecoregion is shown  in Figure 31.
                                                        These results may not be extrapolated to an
                                                        individual state or stream within  the ecoregion
                                                        because the study design was not intended to
                                                        characterize stream conditions at these finer scales.
       Southern Plains Ecoregion
             19,263 miles
 Macroinvertebrate Index
            22%
           i 20%
                                                                       Streambed Sediments
                                                                             M
                                                                             —11
                                                            H 67%
                                                                       Acidification
0     20      -(0      60
         Percentage Stream Length
  For Macroinvertebrate Index:
  • Good n Fair d Poor  D Not Assessed
  For O/ETaxa Loss:
  D > 50% Taxa Loss   D 20-50% Taxa Loss
  D 10-20% Taxa Loss  •< 10% Taxa Loss
  n Not Assessed
                                         20     40     60
                                            Percentage Stream Length
                                    H Low
                                    n Medium
                                    E3 High
                                    n Not Assessed
    20     40      00     80
        Percentage Stream Length
B Good
IH Fair
0 Poor
D Not Assessed
Figure 31. WSA survey results for the Southern Plains ecoregion (U.S. EPA/WSA). Bars show the
percentage of stream length within a condition class for a given indicator. Lines with brackets represent the
width of the 95% confidence interval around the percent of stream length. Percents may not add up to 100
because of rounding.
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                                                  Chapter 3   Wadeable Streams Assessment Ecoregion Results
   During a series of WSA workshops conducted
to evaluate assessment results, professional
biologists working in the Southern Plains
ecorcgion said that no undisturbed streams
remain in the ecoregion. The least-disturbed
streams are those that retain natural configuration
and have riparian buffer zones.

Biological Condition
 • The Macroinvertebrate Index reveals that
   54% of stream length in the Southern Plains
   ecoregion is in poor condition, 20% is in
   fair condition, and 22% is in good condition
   compared to least-disturbed reference
   condition. There are no data for the remaining
   4% of stream length.
 • The O/E Taxa Loss results show that 50% of
   stream length in the Southern Plains ecorcgion
   has lost 10% or more of the macromvertebrate
   taxa expected to occur, and 1 5% has lost more
   than 50% of taxa. These results also indicate
   that 42% of the ecoregion's stream length
   has retained 90% of the groups or classes of
   organisms expected to occur based on least-
   disturbed reference condition.

Indicators of Stress
   The most widespread indicators of stress
in the Southern Plains ecoregion include total
phosphorus, total nitrogen, m-stream fish habitat,
and riparian vegetative cover.

 • Forty-eight percent of stream length in
   the Southern Plains ecoregion has high
   phosphorus concentrations,  7% has medium
  phosphorus concentrations, and 45% has low
  phosphorus concentrations based on least-
  disturbed reference condition.
• Approximately 36% of the ecoregion's stream
  length has high nitrogen concentrations, 30%
  has medium nitrogen concentrations, and
  34% has low nitrogen concentrations based on
                   O
  least-disturbed reference condition.
• Riparian disturbance in this ecoregion is at
  high levels in 19% of stream length. The
  majority of stream length (67%) has medium
  levels of riparian disturbance, and only 14%
  has low  levels for this indicator.
• Salinity  is found at high levels in 22% of
  stream length, at medium  levels in 21% of
  stream length, and at low levels in 57% of
  stream length.
• Streambed sediments are rated poor in 30% of
  stream length, fair in 18%, and good in 52%
  based on least-disturbed reference condition.
• In-stream fish habitat is in poor condition in
  42% of  stream length, fair in  23% of stream
  length, and good in  35% of stream length
  based on least-disturbed reference condition.
• Vegetative cover in the  riparian zone along
  stream banks is in poor condition  for 36% of
  stream length, in fair condition for 40% of
  stream length, and good condition for 24% of
  stream length.
• I he effects of acidification are not noted for
  the Southern Plains  ecoregion.
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Chapter 3   Wadeable Streams Assessment Ecoregion Results
Northern Plains Ecoregion

Physical Setting
   The Northern Plains ecoregion covers approxi-
mately 205,084 mi2 (6.8% of the United States),
including the western Dakotas, Montana east of
the Rocky Mountains, northeast Wyoming, and
a small section of northern Nebraska. Federal
lands account for 52,660 mr or a relatively large
(25.7%) share of the total area. The Great Prairie
grasslands were also an important feature of this
ecoregion, but about 90% of these grasslands have
been replaced by other vegetation or land use. The
ecorcgion's terrain is irregular plains interspersed
with tablelands and low hills. This ecoregion is
the heart of the Missouri River system and is
almost exclusively within the Missouri River's
regional watershed. The total stream length
represented in the WSA for the Northern Plains
ecoregion is  13,445 wadeable stream miles.
   Land use is arable with grazing or semi-
arid grazing. Based on satellite images in the
1992 NLCD, die distribution of land cover
in this ecoregion is 56% grassland and 30%
planted/cultivated, with the remaining 1 4% oi
tho ecoregion comprised of other types of land
cover. Significant wetlands arc also found in the
Nebraska Sandhills area. The climate is dry and
continental, characterized by short, hot summers
and long, cold winters. Temperatures average 36 to
46 °F, and annual precipitation totals range from
10 to 25 inches. High winds are an important
climatic factor in this ecoregion. It is also subject
to periodic, intense droughts and frosts.
Biological Setting
   The predominant vegetative cover for the
Northern Plains ecoregion was formerly native
short prairie grasses, such as wheat grass and
porcupine grass, but now cropland i.s much more
prevalent.
                 Wolf Creek, McCook County, SD, in the Northern Plains ecoregion
                 (Photo courtesy of Dynamac Corp).
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                                                    Chapter 3   Wodeob/e Streams Assessment Ecoregion Results
Human Influence
   Human economic activity is primarily
agriculture, including cattle and sheep grazing,
as well as the growing of wheat, barley, and
sugar beets. Coal mining occurs in the  North
Dakota, Montana, and  Wyoming portions of
the ecoregion. Petroleum and gas production has
grown considerably in the Cur Bank region in
north-central Montana. There are several large
Indian reservations in this ecoregion, including
the Pine Ridge,  Standing Rock, and Cheyenne
reservations in South Dakota and the Blackfeet,
Crow, and Port  Peck  reservations in Montana.
There are currently four active and one proposed
hi'A Superfund  National Priority hist sites in this
ecoregion.
                      The approximate population of this ecoregion
                    is relatively small at 1,066,000, or 0.4% of the
                    population of the United States.

                    Summary ofWSA Findings
                      A total of 98 random sites were sampled during
                    the summers of 2000-2004 to characterize the
                    condition of wadeable streams throughout the
                    Northern Plains ecoregion. An oven lew of the
                    WSA survey results for the ecoregion is shown in
                    Pigure 32. These results may not be extrapolated
                    to an individual state or stream within  the
                    ecoregion because the study design was not
                    intended to characterize stream conditions at
                    these finer scales.
                                    Phosphorus
                                                        54%
                                                           60%
       Northern Plains Ecoregion
            13,445 miles
                                                             66%
      20      40     60
         Percentage Scream Length
  For Macroinvertebrate (ndex:
  • Good D Fair EE Poor D Not Assessed
  For O/E Taxa Loss:
  H > 50% Taxa Loss   D 20-50% Taxa Los!
  D 10-20% Taxa Loss  •<  10% Taxa Loss
I  D Not Assessed
    20     40      60
        Percentage Stream Length
f Low
n Medium
0 High
D Not Assessed
                                  Streambed Sediments
                                         14%
                                      •
                                   < 3%
                                                                                          50%
                                                                       Riparian Vegetative Cover
                                                                                  I 28%
                                                                                < 22%
                                                                       Acidification
    20     40      60     80
        Percentage Stream Length
H Good
D Fair
EJ Poor
n Not Assessed
Figure 32. WSA survey results for the Northern Plains ecoregion (U.S. EPA/WSA). Bars show the
percentage of stream length within a condition class for a given  indicator. Lines with brackets represent the
width of the 95% confidence interval around the percent of stream length. Percents may not add up to  100
because of rounding.
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Chapter 3   Wadeable Streams Assessment Ecoregion Results
   During a series of WSA workshops conducted
to evaluate assessment results, professional
biologists working in the Northern Plains
ecoregion said that although the ecoregion
has relatively few undisturbed streams, the
majority are in areas of low-level agriculture and
pastureland.

Biological Condition
  • The Macroinvertebrate Index reveals that
   50% of stream length in the Northern Plains
   ecoregion is in poor condition,  13%  is in
   fair condition, and 30% is in good condition
   compared to least-disturbed reference
   condition. There are no data for the remaining
   7% of stream length.
  • The O/E Taxa Loss results show that 34% of
   stream length has lost 10% or more of the
   macroinvertebrate taxa expected to occur,
   and 12% has lost more than 50% of taxa.
   These results also indicate that 60% of the
   ecoregion's stream length has retained 90% of
   the groups or classes of organisms expected
   to occur based on least-disturbed reference
   condition.

Indicators of Stress
   The most widespread  indicators of stress in
the Northern Plains ecoregion include riparian
vegetative cover, in-stream fish habitat, riparian
disturbance, and salinity.

  • Thirty-three percent of stream length in
   the Northern Plains ecoregion has high
   phosphorus concentrations, 13% has medium
   phosphorus concentrations, and 54% has low
   phosphorus concentrations based on least-
   disturbed reference condition.
• Eighteen percent of the ecoregion's stream
  length has high nitrogen concentrations, 21%
  has medium nitrogen concentrations, and
  60% has low nitrogen concentrations based on
  least-disturbed reference condition.
• Riparian disturbance in the Northern Plains
  ecoregion is at high levels in 31% of stream
  length, at medium levels in 66% of stream
  length, and at low levels in 3% of stream
  length.
• Salinity is a significant stressor in the Northern
  Plains. Salinity is high in 38% of stream
  length, medium in 22% of stream length, and
  low in 40% of stream length.
• Streambed sediments arc rated poor in 33%
  of stream length in the Northern Plains
  ecoregion, fair in  14%, and good in 50%
  based on least-disturbed reference condition;
  data for this indicator were unavailable for 3%
  of stream length.
• In-stream fish habitat is in poor condition in
  45% of stream length, fair in 21% of stream
  length, and good in 34% of stream length
  based on least-disturbed reference condition.
• Vegetative cover in the riparian zone along
  stream banks is in poor condition for 50% of
  stream length, in fair condition for 22% of
  stream length, and in good condition for 28%
  of stream length.
• The effects of acidification are not noted  for
  the Northern Plains ecoregion.
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                                                 Chapter 3   Wadeable Streams Assessment Ecoreg/on Results
Western Mountains
Ecoregion

Physical Setting
   The Western Mountains ecoregion includes
the Cascade, Sierra Nevada, and Pacific Coast
ranges in the coastal states; the Cila Mountains
in the southwestern states; and the Bitteroot
and Rocky mountains in the northern and
central mountain states. This ecoregion covers
approximately 397,832 mi2, with about 297,900
mi2 or 74.8% classified as federal land — the
highest proportion of federal property among all
the 9 aggregate ecoregions. The terrain of this
area is characterized by extensive mountains and
plateaus separated by wide valleys and lowlands.
Coastal mountains are transected by numerous
fjords and glacial valleys, are bordered by coastal
plains, and include important estuaries along
the ocean margin. Soils are mainly nutrient-poor
forest soils. Based on  satellite images in the 1992
NLCD, the distribution of land cover in this
ecoregion is  59% forested, 19% shrubland, and
13% grassland, with the remaining 9% of the
ecoregion comprised  of other types of land cover.

   The headwaters and upper reaches of the
Columbia, Sacramento, Missouri, and Colorado
river systems all occur in this ecoregion. Smaller
rivers share many characteristics, starting  as steep
mountain streams with staircase-like channels
and steps and plunge pools, with riffles and
pools appearing as slope decreases. Upper river
reaches experience debris flows and landslides
when shallow soils become saturated by rainfall or
snowmelt. The total stream length represented in
the WSA for the Western Mountains ecoregion is
126,436 wadeable stream miles.
Unnamed tributary to Lake Creek, Chelan County,
WA, in the Western Mountains ecoregion (Photo
courtesy of the Washington Department of Ecology).

   The climate is sub-arid to arid and mild in
southern lower valleys, and humid and cold at
higher elevations. The wettest climates of North
America occur in the marine coastal rain forests of
this ecoregion. Mean annual temperatures range
from 32 to 55 °F, and annual precipitation ranges
from 16 to 240 inches.
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Chapter 3   Wodeob/e Streams Assessment Ecoreg/on Results
Biological Setting
   Rivers in this ecoregion drain dense forested
catchments and contain large amounts of woody
debris that provide habitat diversity and stability.
Rivers reaching the Pacific Ocean historically had
large runs of salmon and trout, including pink,
chum, sockeye, coho, and chinook salmon, as well
as cutthroat and steelhead trout. Many of these
anadromous fish populations have been  reduced
since the time of European settlement due to the
effects of overfishing, introduced species, flow
regulations, and dams. Spawning habitats in
stream pools have been drastically reduced due to
increased sediments from logging, mining, and
other land use changes.

Human  Influence
   Deforestation and urbanization continue to
alter stream habitats in the mountainous west.
The Western  Mountains riparian ecosystems first
encountered pressure from grazing and mining
from the mid-f 800s to about f 910  and  then from
the logging roads and fire management practices
that occur to  the present day.

   Placer mining, which  disrupts stream sediment
habitats, was  once widespread in the Western
Mountains ecoregion. Particularly damaging
in mountainous areas was the introduction of
mercury, which was used extensively in placer
mining  for gold. Toxic contaminants from
mining  also include arsenic, antimony, copper,
chromium, cadmium, nickel, lead, selenium,
silver, and zinc. In addition to mining, other
activities such as logging, grazing, channelization,
dams, and diversions in the Sierra Nevada
area also significantly impacted rivers and
streams. Introduced fish  provided further stress,
with several native fish species threatened or
endangered.
   The principal economic activities in this
ecoregion are high-tech manufacturing, wood
processing, international shipping, U.S. naval
operations, commercial fishing, tourism, grazing,
and timber harvesting. Hydroelectric power
generation is prevalent in the Pacific Northwest
area and California. Bauxite mining also occurs in
th; Pacific Northwest portions of the ecoregion.
There are currently 74 active,  7 proposed, and
22 deleted EPA Superfund National Priority List
sites in the Western  Mountains ecoregion.

   The approximate population in the Western
Mountains ecoregion is 9,742,192, representing
approximately 3% of the population of the
United States.

Summary ofWSA Findings
   A total of 529 random sites were sampled
during the summers of 2000-2004 to characterize
the condition of wadeable streams throughout
the Western Mountains ecoregion. This ecoregion
had the greatest number of sample sites because
all the western states enhanced the scale of the
national survey by including additional random
sites. Although there are enough sites to develop
state-scale estimates of condition, this report did
not produce those estimates. The individual states
are analyzing the survey results in the context of
their own water quality standards and assessment
methodologies. An overview of the WSA survey
results for the Western Mountains ecoregion is
shown  in P'igure 33. These results may not be
extrapolated to an individual state or stream
within  the ecoregion.

   During a series of WSA workshops conducted
to evaluate assessment results, professional
biologists working in the Western Mountains
ecoregion said that many least-disturbed streams
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                                                     Chapter 3   Wadeable Streams Assessment Ecoregion Results
 in the ecoregion arc of relatively high quality;
 however, some of these streams have mining and
 logging impacts, leading to reference conditions
 of varying degrees of quality.

 Biological Condition
  • The Macroinvertebrate Index reveals that 25%
   of stream length in the Western Mountains
   ecoregion is in poor condition, 28% is in
   fair condition, and 46%  is in good condition
   compared to least-disturbed reference
   condition. There are no data for about 1% of
   stream  length.
  • 'Hie O/E Taxa Loss results show that 33% of
   stream  length has lost 10% or more of the
   macroinvertebrate taxa expected to occur, and
   5% has lost  more than 50% of taxa. These
                       results indicate that 63% of stream length
                       has retained 90% of the groups or classes of
                       organisms expected to occur based on least-
                       disturbed reference condition.

                    Indicators  of Stress
                       The most widespread indicators of stress in
                    the Western Mountains ecoregion include total
                    nitrogen, total phosphorus, riparian disturbance,
                    and streambed sediments.
                     • Sixteen percent of stream length in the
                       Western Mountains ecoregion has high
                       phosphorus concentrations, 25% has medium
                       phosphorus concentrations, and 59% has low
                       phosphorus concentrations based on least-
                       disturbed reference condition.
                                                                                               63%
                                                                                                 70%
                                   Streambed Sediments
                                     	     22%
                                     BH 14%
                                   1%
                                   In-stream Fish Habitat
     Western Mountains Ecoregion
            126,436 miles
0     20      40      60
         Percentage Stream Length
  For Macroinvertebrate Index:
  • Good G Fair M Poor  Q Not Assessed
  For O/E Taxa Loss:
  H > 50% Taxa Loss   d 20-50% Taxa Loss
  Cl 10-20% Taxa Loss • < 10% Taxa Loss
  L"H Not Assessed
           40      60
        Percentage Stream Length
U Low
D Medium
• High
n Not Assessed
100  0      20      40     60      80      100
             Percentage Stream Length
    | Good
    D Fair
    El Poor
    D Not Assessed
Figure 33. WSA survey results for the Western Mountains ecoregion (U.S. EPA/WSA). Bars show the
percentage of stream length within a condition class for a given indicator. Lines with brackets represent the
width of the 95% confidence interval around the percent of stream length.  Percents may not add up to 100
because of rounding.
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Chapter 3   Wadeable Streams Assessment Ecoregion Results
   Seventeen percent of the ecoregion's stream
   length has high nitrogen concentrations, 28%
   has medium nitrogen concentrations, and
   54% has low nitrogen concentrations based on
   least-disturbed reference condition.
   Riparian disturbance, or evidence of human
   influence in the riparian zone, is at high levels
   in 14%  of stream length, at medium levels
   in 47%  of stream length, and at low levels in
   39% of stream length.
   Levels of salinity are medium in 3% of stream
   length and low in 97% of stream length.
   None of the stream length for the Western
   Mountains ecoregion had high levels of
   salinity.
• Streambed sediments are rated poor in 14% of
  stream length in this ecoregion, rair in 22%,
  and good in the remaining 63%.
• In-strcam fish habitat is in poor condition in
  9% of stream length, fair in 20% of stream
  length, and good in 70% of stream length.
• Vegetative cover in the riparian zone along
  stream banks is in poor condition for 9% of
  stream length, in fair condition for 32% of
  stream length, and in good condition for 59%
  of steam length.
• Acidification is rated poor in nearly 1% of
  stream length and good in 99% of stream
  length.
           Fishing and tourism are important economic activities in the Western Mountains
           ecoregion (Photo courtesy of Ron Nichols, U.S. Department of Agriculture National
           Resources Conservation Service).
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Xeric  Ecoregion
Physical Setting
   The Xeric ecoregion covers the largest area of
all WSA aggregate ecorcgions and includes the
most total land under federal ownership. This
ccoregion covers  portions of eleven western states
and all of Nevada for a  total of about 636,583
mi' (21.2% of the United States). Some 453,000
mi2 or 71.2% of  the land is classified as federal
lands, including  large tracts of public land,
such as the Grand Canyon National Park, Big
Bend  National Park, and the Hanford Nuclear
Reservation. Tribal lands include the Navajo,
Hopi, and Yakima reservations. Based on satellite
images in the 1992 NLCD, the distribution of
land cover in this ecoregion is 61 % shrubland and
1 5% grassland, with the remaining 24%  of the
ecoregion comprised of other types of land cover.
Chapter 3   Wadeable Streams Assessment Ecoregion Results

       The Xeric ccoregion is comprised of a mix
    of physiographic features, including plains with
    hills and low mountains, high-relief tablelands,
    piedmont, high mountains, and intermountain
    basins and valleys.  The ecoregion includes the
    flat to rolling topography of the Columbia/Snake
    River Plateau; the Great Basin; Death Valley;
    and the canyons, cliffs, buttes, and mesas of the
    Colorado Plateau. All  of the non-mountainous
    area of California falls in the Xeric ecoregion and
    is distinguished by a mild Mediterranean climate,
    agriculturally productive valleys, and large
    metropolitan areas.

       This ecoregion's relatively limited surface
    water supply contributes to the Upper and Lower
    Colorado, Great Basin, California, Rio Grande,
    and Pacific Northwest regional watersheds. Large
    rivers flow all year,  are supplied by snowmelt,
               West Clear Creek,Yavapai County, AZ, in the Xeric ecoregion
               (Photo courtesy of the Arizona Game and Fish Department/USGS).
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Chapter 3   Wodeob/e Streams Assessment Ecoreg/on Results
and peak in early summer. Small rivers in this
ecoregion are mostly ephemeral. Most rivers are
turbid because they drain erodable sedimentary
rock in a dry  climate, where sudden  rains flush
sediments down small rivers. Rivers are  often
subject to rapid change due to flash floods and
debris flows. In southern areas, dry conditions
and water withdrawals produce internal drainages
that end in saline lakes or desert basins without
reaching the ocean (e.g., Utah's Great Salt Lake).
The total stream length represented in the WSA
for the Xeric ecoregion is 25,989 wadcable stream
miles.

   The Xeric  ecoregion's climate vanes widely
from  warm and dry to temperate, with mean
annual temperatures ranging from 32 to 75 °F
and annual precipitation in the 2- to 40-inch
range. The dry weather in the Sonoran, Mojavc,
and Chihuahuan deserts is created by the rain
shadows cast by the mountains to the west and is
punctuated by heavy, isolated episodic rainfalls.
Biological Setting
   Rivers create a riparian habitat oasis for plants
and animals in the dry Xeric ecoregion areas.
Many fish are endemic, are restricted to the
Colorado River basin, and have evolved to cope
with warm, turbid waters. Examples include
the humpback chub, bonytail chub, Colorado
pikeminnow, roundtail chub, razorback sucker,
Colorado squawfish, Pyramid Lake cui-ui, and
Lahontan cutthroat trout. Most of these fish
are threatened or endangered as a result of flow
regulations from dams, water withdrawals, and
introduced non-native species. Threatened species
offish in desert areas include the Sonora chub
and beautiful shiner.
Human Influence
   Impacts to the Xeric ecoregion riparian
habitats have been heavy in the past 250 years
because of water impoundment and diversion;
groundwater and surface water extraction; grazing
and agriculture; and mining, road development,
and heavy recreational demand. Both the least-
altered and most-altered  pre-settlement natural
vegetation types are found in this ecoregion.
Riparian habitats in this  ecoregion have also
been widely impacted by invasive species and
contamination from agriculture and urban runoff.
Big rivers in the southwestern canyon regions
were altered due to large  dam construction
and large-scale water-removal projects for cities
and agriculture, with attendant small  streams
that experience cycles of draining and filling in
response to grazing, groundwater withdrawal,
and urbanization. In many desert areas,
dissolved solids such as boron, molybdenum,
and organophosphates leach from desert soils
into irrigation waters. Almost every tributary in
California's Central Valley has been altered by
canals, drains, and other  waterways.

   Principal economic activities include recreation
and tourism; mining; agriculture; grazing;
manufacturing and service industries; agriculture
and food processing; aerospace and defense
industries; and automotive-related industries.
Petroleum production is  prevalent in California.
Agriculture includes production of a wide range
of crops, from wheat, dry peas, lentils, and
potatoes to grapes and cotton. Large agricultural
irrigation projects include the Salt and Gila valleys
and the Imperial  and Central valleys in California.
There are currently 139 active, 6 proposed, and
24 deleted EPA Superfund National Priority List
.sites in this ecoregion.
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                                                   Chapter 3   Wadeable Streams Assessment Ecoregion Results
   The total population in the Xeric ccoregion
is the third largest of all WSA ecorcgions at
approximately 46,800,000 people, or 16% of the
population of the United  States.

Summary of WSA Findings
   A total of 176 random  sites were sampled
during the summers of 2000—2004 to characterize
the condition of wadeable streams throughout the
Xeric ecorcgion. An overview of the WSA survey
results for the Xeric ecoregion is shown in Figure
34. These results may not be extrapolated to an
individual state or stream  within the ecoregion.

   During a series of WSA workshops condticted
to evaluate assessment results, professional
biologists working in  the Xeric ecorcgion said that
many of the perennial, least-disturbed streams in
                   this ecoregion have been influenced by past and
                   current human activities.

                   Biological Condition
                    • The Macroinvertebrate Index reveals that 39%
                      of stream  length in the Xeric ccoregion is in
                      poor condition compared to least-disturbed
                      reference condition, 15% is in fair condition,
                      and 42%  is in good condition. There are no
                      data for about 4% of stream length.
                    • The O/E Taxa Loss results show that 60% of
                      stream length in the Xeric  ccoregion has lost
                      10% or more of the macroinvertebrate taxa
                      expected to occur and  1 5% has lost more than
                      50% of taxa. These results also indicate that
                      34% of stream length has retained 90%  of the
                      groups or classes of organisms expected to  occur
                      based on least-disturbed reference condition.
                                                         60%
           Xeric Ecoregion
            25,989 miles
      20      40     60
         Percentage Stream Length
  For Macroinvertebratc Index:
  • Good D Fair H Poor D Not Assessed
  For O/E Taxa Loss:
  • > 50% Taxa Loss   Q 20-50% Taxa Loss
  D 10-20% Taxa Loss  • < 10% Taxa Loss
  n Not Assessed
           40      60
        Percentage Stream Length
H Low
CD Medium
• High
D Not Assessed
                                  j Streambed Sediments
                                         •I
                                          17%
100  0      20     40     60
             Percentage Stream Length
    H Good
    D Fair
    H Poor
    n Not Assessed
Figure 34. WSA survey results for the Xeric ecoregion (U.S. EPA/WSA). Bars show the percentage of
stream length within a condition class for a given indicator. Lines with brackets represent the width of the 95%
confidence interval around the percent of stream length. Percents may not add up to 100 because of rounding.
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Chapter 3   Wbdeob/e Streams Assessment Ecoreg/on Results
Indicators of Stress
  The leading indicators of stress in the Xeric
ecoregion include riparian disturbance, total
nitrogen, streambed sediments, and in-stream fish
habitat.

 • Twenty-nine percent of stream length in
   the Xeric ecoregion has high phosphorus
   concentrations, 10% has medium phosphorus
   concentrations, and 60% has low phosphorus
   concentrations based on least-disturbed
   reference condition.
 • Nitrogen is the leading chemical stressor in the
   Xeric region. Approximately 36% of stream
   length has high nitrogen concentrations, 26%
   has medium nitrogen concentrations, and
   37% has low nitrogen concentrations based on
   least-disturbed reference condition.
 • Riparian disturbance, or evidence of human
   influence in the riparian zone, is the leading
   physical stressor for the Xeric ecoregion.
   Riparian disturbance in  this ecoregion is
   at high levels in 44% of stream length, at
   medium levels in 40% of stream length, and at
   low levels in 15% of stream length.
• Salinity is rated high in 13% of stream length
  and medium in 29%, with 56% of stream
  length showing low levels of this indicator.
  Data for this indicator were unavailable for
  approximately 1% of stream length.
• Streambed sediments are rated poor in 32%
  of stream length in the Xeric ecoregion, fair in
  17%, and good in 48%; data on this indicator
  were unavailable for 3% of stream length.
• In-stream habitat is in poor condition in
  27% of stream length, fair in 25%, and good
  in 47% based on least-disturbed reference
  condition; data were unavailable for 1% of
  stream  length.
• Vegetative cover in the riparian zone along
  stream  banks  is in poor condition  in 28% of
  stream  length, in fair condition in 21% of
  stream  length, and in good condition in 49%
  of stream length.
• The effects of acidification are not noted for
  the Xeric ecoregion.
The Xeric ecoregion is
comprised of a mix of
physiographic features,
including plains with
hills and low mountains,
high-relief tablelands,
piedmont, high mountains,
and intermountain
basins and valleys (Photo
courtesy of Tim McCabe, U.S.
Department of Agricultural
Natural Resources
Conservation Service).
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  Chapter 4
Summary and Next Steps

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Chapter 4   Summary and Next Steps
Summary and  Next

Steps

Summary
   The United States covers an enormous and
diverse landscape, and not surprisingly, the
biological condition of the nation's streams varies
widely geographically. Overall, 42% percent of
the nation's stream length is in poor biological
condition compared to least-disturbed reference
condition in each of the WSA ccoregions.
The Eastern Highlands region has die largest
proportion of streams in poor biological
condition (52%), whereas the West has the lowest
proportion (27%). In the Plains and Lowlands
region, 40% of stream length is in poor biological
condition.
   Stream miles,  represented as stream length,
are not evenly distributed across the country.
The densest  coverage of perennial streams  in
the lower 48 states is  in the Eastern Highlands
region, which has approximately 276,362  miles
of perennial  streams and the smallest land  area of
the three major regions.  1 he Plains and Lowlands
region, which covers the largest portion of the
United States, has 242,264 miles of perennial
streams.  The West has 152,425 miles of streams.
It is important to evaluate the survey results in
terms of both stream  length percentages and
absolute stream miles in each condition class. Lor
example, the percentage of stream length in good
condition varies dramatically between the  West
(45%) and Plains and Lowlands regions (29%);
however, if rhcse percentages are converted to
stream miles, the West has 68,672 miles in good
condition, whereas the Plains and Lowlands
region has 70,257 miles in good condition.

  T he WSA finds that the most widespread
or common strcssors are elevated levels of the
nutrients nitrogen and phosphorus, riparian
disturbance, and excess streambed sediments.
Nationally, 32% of stream length (213,394 miles)
has high concentrations of nitrogen compared
to least-disturbed reference conditions, and
31% (207,355 miles) has  high concentrations of
phosphorus. Iwenty-six percent of the nation's
stream length (171,118 miles) has high levels
of riparian disturbance (e.g., human influence
along the riparian zone), and 25% (167,092
miles)  has streambed sediment characteristics
in poor condition. Analysis of the association
between stressors and biological condition finds
that high levels of nutrients and excess streambed
sedimentation more than  double the risk of poor
biological condition.

  The WSA provides the first nationally
consistent baseline of the  condition of the
nation's streams. This baseline will be used
in future assessments to evaluate changes in
conditions and to provide insights as to the
effectiveness of water resource management
actions. Highlight: Acidification Trends and the
Clean Air Act illustrates how this type of survey
c;.n be used to evaluate the effectiveness of
management actions on improving water quality.
Slates, EPA, and other partners plan to use this
approach to  implement large-scale assessments of
lakes in 2007 and similar  assessments of rivers,
wetlands, and coastal waters in  future years.
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                                                                   Chapter 4   Summary and Next Steps
Acidification Trends and the Clean Air Act

   Although thisWSA provides a snapshot of the current conditions in the nation's streams, future
surveys will allow us to detect trends in stream conditions and in the stressors that affect them.  One
example in which probability-based survey designs were implemented  repeatedly over the course of
10 years has been the evaluation of the responsiveness  of acid-sensitive lakes and streams to changes
in policy and management actions. Title IV of the 1990  Clean Air Act Amendments (CAAA) set target
reductions for sulfur and nitrogen emissions from industrial sources as a means of reducing the
acidity in deposition.  One of the intended effects of the reductions was to decrease the acidity of
low-alkalinity waters. A 2003  EPA report by Stoddard et al., assessed recent changes in surface water
chemistry in the northern and eastern United States to evaluate the effectiveness of the CAAA. At the
core of the monitoring, known as the Temporally Integrated Monitoring of Ecosystems (TIME) project,
was the concept  of a probability survey, where a set of sampling sites was chosen to be statistically
representative of a target population. In the Northeast (New England and Adirondacks), this target
population consists of lakes likely to be responsive to changes in rates of acidic deposition.  In the
Mid-Atlantic, the  target population is upland streams with a high probability of responding to changes
in acidic deposition. Repeated surveys of this population allowed an assessment of trends and changes
in the number of acidic systems during the past decade. The trends reported in the following table
are for recovery from chronic acidification. The analysis found that during the 1990s, the amount of
acidic waters in the target population declined. The number of acidic lakes in the Adirondacks dropped
by 38%, and the number of acidic lakes in  New England  dropped by 2%. The length of acidic streams
declined by 28% in the Mid-Atlantic area.
Estimates of change in number and proportion of acidic surface waters in acid-sensitive regions
 of the northern and eastern United States. Estimates are based on applying current rates of
change in Gran  ANC* to past estimates of population characteristics from probability surveys.


Region
New England
Adirondacks
Mid-Atlantic


Number of
Lakes
6,834 lakes
1,830 lakes
42,426 km


Number
Acidic"
386 lakes
238 lakes
5,014 km


Acidic'
5.6%
13.0%
1 1.8%
Time
Period
of
Estimate
1991-1994
1991-1994
1993-1994
Current
Rate of
ANC
Changed
+0.3
+0.8
+0.7
Estimated
Number
Currently
Acidic6
374 lakes
149 lakes
3,600 km

Current
Acidic
5.5%
8.1%
8.5%
Change
in
Number
of Acidic
Systems
-2%
-38%
-28%
 •' For both Northeast lakes and Mid-Atlantic streams, waterbodies with ANC (using the analytical technique of Gran deration,
  with the result known as "Gran ANC") of < 100 ^eq/L are particularly vulnei-,ib\c
 b Number of lakes/streams with Gran ANC < 0 in past probability survey (d.itn collected at "Time Period of Estimate" in column 5).
 4 Percent of population (from Column 2) with Gran ANC < 0 in pasr probability survey (data collected at "Time Period of Estimate" in column 5).
 d Based on regional trends in ueq/L/year.
 c Based on trends from repeated surveys through 2001.
                                TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter 4   Summary and Next Steps
Next Steps
   In addition to characterizing the biological
condition of the nation's stream resources, the
WSA provides a rich data set that has sparked
interest in many additional areas of investigation.
These include the following:

 • Support Protection and Restoration
   Actions - The WSA finds that between 25
   and 32% of stream length is rated poor due
   to high levels of nutrients or excess streambed
   sedimentation. These streams are two times
   more likely to score poor for biological
   condition than streams with low levels of
   these  parameters. This national-scale finding
   reinforces reports from states and the USGS
   on specific watersheds and stream segments
   that identify nutrients and streambed
   sedimentation as  leading water quality
   stressors. EPA is pursuing opportunities to
   use the WSA data in combination with other
   data to inform decision-makers responsible
   for water resource protection and restoration
   actions. Specific actions in the short term
   include analyzing the WSA dataset to
   determine associations between watershed
   characteristics (e.g., size, slope, and soil type)
   to help target where improvements are needed;
   using these characteristics in conjunction
   with information on the effectiveness of best
   management practices (BMPs) to help identify
   successful non-point source pollution controls;
   and supporting states' development of water
   quality standards for nutrients and sediments.
 • Future Designs — It is clear that future
   surveys will continue to be based on sample
   survey designs and that  the detection of
   changes and trends will  be of greater interest;
   therefore, future survey  designs will include
provision for estimating both current
status and future trends. This will require a
determination of the number of sites that are
revisited versus new sites. Current analyses
of variance components suggest that in
future surveys, a substantial percentage of the
sites (possibly 20—50%) should be replaced
with new sites and that this replacement
should continue with each new survey.
This replacement will help detect change;
incorporating new sites will improve  future
status assessments and reduce the likelihood
that bias will be introduced by repeated
sampling of the same locations. As individual
states and tribes begin adopting sample survey
designs into their programs, the results from
their efforts can be incorporated into the
national assessments.
Indicators -This initial assessment was
unable to  incorporate a large .set of biological
and stressor indicators because of a short
planning timeline.  In future national
stream surveys, the WSA will consider
including fish assemblages, algal assemblages
(e.g., periphyton in streams), fish tissue
contamination by metals and organics,
and/or sediment contamination assessed
through either sediment metal and organic
chemistry or sediment toxicity tests, tt will
also be possible to add emerging stressor
indicators of concern. This will allow for
a more comprehensive assessment of both
the conditions in wadeable streams and the
stressors potentially affecting them.
Field Protocols — The field protocols used
for  the WSA are widely used and were well
tested across the country. These protocols
have demonstrated a strong ability to detect
environmental signals against the background
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of natural variability. For this initial assessment
of wadeable streams, using the same protocols
across the country reduced the complexity of
interpreting the results; however, for future
national stream surveys, the use  of different
yet comparable methods will be  evaluated for
different types of streams (e.g., low gradient
vs. high gradient). EPA and the  states will
also explore integrating and sharing data from
multiple sources, as well as options to improve
sample collection methods.
Reference Conditions — Stream ccologists
and state and federal managers agree that they
should be able to describe least-disturbed
reference condition at a more refined spatial
scale than that of the nine regions presented
in the WSA. To do so will require substantial
coordinated efforts among state, tribal, and
federal partners. There are also likely to be
some regions of the country in which land-
use changes have been  so dramatic that even
the "best" streams may have experienced
substantial chemical, physical, and biological
            Chapter 4   Summary and Next Steps

degradation. Additional research will be
required to provide a better solution to setting
expected conditions for those regions of the
country.
Stressor Ranking - The presentation on
stressors in the WSA showed both their
extent (i.e.,  the percent of stream length with
excessive levels of the stressors) and relative
risk (i.e., the increased chance of finding poor
biological condition). To make the best use
of this information, the WSA must look for
stressors that have both high relative risk and
large extent. The human health assessment
community combines these two sets of
information into a single number called the
"population attributable relative risk." If,
during investigation, this summary number
proves reliable for ecological studies, it will
simplify the ranking of stressors in future
assessments. However, use of more than one
biological assemblage in future assessments
will result in multiple relative risk values,
one for each biological indicator. It would
                                 The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Chapter 4   Summary and Next Steps
   not be surprising if EPA and its partners find
   that the relative risk posed by each stressor
   depends on the biological community being
   evaluated. Although these added numbers may
   complicate the ranking of stressors, they will
   also aid in understanding which component
   of the stream biota is sensitive to each stressor
   and will provide additional options for
   management.
 • Future National Assessments   EPA and its
   state, tribal, and federal partners will produce
   national assessments of waterbody types
   on a yearly cycle. For lakes and  reservoirs,
   a field survey will occur in 2007 with a
   national assessment report of the results in
   2009. Rivers will be surveyed in 2008, and
   a national assessment report will follow in
   2010. Wadeable streams will be surveyed
   again in 2009, and the assessment report
   that follows in 2011 will  include all flowing
   waters  - both rivers and streams. That report
   will also evaluate any changes in biological
   condition that occurred in streams. An NCCR
   assessment will be  repeated in 201 2, with the
   results  of the field survey from 2010. Wetlands
   will be surveyed  during the 2011 samp ing
   season, followed by a national assessment
   report  in 2013. Erom that point on, the
   surveys and national assessment reports will be
   repeated in sequence, with changes and trends
   becoming a greater focus for each resource
   survey.
   The continued utility of these national surveys
and their assessment reports  requires continued
consistency in design, as well as in  field, lab,
and assessment methods from assessment to
assessment; however, the surveys must also
provide flexibility that allows the science of
monitoring to improve over  time. Maintaining
consistency while allowing flexibility and growth
wiil be one of the many challenges facing the
national assessment program in coming years.

   1 his national survey would not have been
possible without the involvement of hundreds of
dedicated scientists working for state, tribal, and
federal agencies and universities across  the United
States. Future surveys will rely on this continued
close collaboration, a free exchange of knowledge,
and a deep well of energy and enthusiasm. It
is EPAs goal that participants translate  the
expertise they gained through these national
surveys to studies of their own waters and use this
substantial and growing baseline of information
to evaluate the success of efforts to protect and
restore the quality of the nation's waters.
The Wadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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                                                      Glossary of Terms
 Glossary  of Terms

Benthic macroinvertebrates: Aquatic larval
stages of insects such as dragonflies; aquatic
insects such as aquatic beetles; crustaceans such
as crayfish; worms; and mollusks.  These small
creatures live  throughout the stream bed attached
to rocks, vegetation, and logs  and sticks or
burrowed  into stream bottoms.
Biological assemblages: Key groups of animals
and plants—such as benthic macroinvertebrates,
fish, or algae—that are studied to learn more
about the  condition of water resources.
Biological integrity: State of being capable of
supporting and maintaining a balanced commu-
nity of organisms having a species composition,
diversity, and functional organi/ation comparable
to that of  the natural habitat of the region.
Ecoregions: Ecological regions that are similar in
climate, vegetation, soil type,  and geology; water
resources within a particular ecoregion have
similar natural characteristics  and similar
responses  to stressors.
In-stream fish habitat: Areas fish need for
concealment and feeding. These areas include
large wood within the stream  banks, boulders,
undercut banks, and tree roots.
Intermittent (ephemeral) streams: Streams that
flow only  during part of the year, such as in the
spring and early  summer after snowmelt.
Macroinvertebrate Index of Biotic Condition:
The sum of a number of individual measures of
biological  condition, such  as the number of taxa
in a sample, the number of taxa with different
habits and feeding strategies, etc.
National Hydrography Dataset: Comprehensive
set of digital spatial data—based on U.S. Geolog-
ical Survey 1:100,000 scale topographic maps—
that contains information on surface water
features such as streams, rivers, lakes, and ponds.

Nutrients: Substances such as nitrogen and
phosphorus that are essential to life but can over-
stimulate the growth of algae and other plants in
water. Excess nutrients in streams and lakes can
come from agricultural and  urban runoff, leaking
septic systems, sewage discharges, and similar
sources.

O/E (Observed/Expected) Ratio of Taxa Loss:
A ratio comparing the number of taxa expected
(E) to exist at a site to the number that arc
actually observed (O). The taxa expected at
individual sites are based on models developed
from data collected at reference sites.

Perennial streams: Streams that flow
continuously throughout the year.

Physical habitat: For streams and rivers, the area
in and around the stream or river,  including its
bed, banks, m-stream and overhanging vegetation,
and riparian zone.

Probability-based design: A type of random
sampling technique in which every element of the
population has a known probability of being
selected for sampling.

Reach: A discrete segment of a stream.

Reference condition: The least-disturbed
condition available in an ecological region;
determined based on specific criteria and used as a
benchmark for comparison with other sample
sites in the region.
                                   TheWadeable Streams Assessment: A Collaborative Survey of the Nation's Streams

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Glossary of Terms

Riparian: Pertaining to a stream or river and its
adjacent area.

Riparian disturbance: A measure of the evidence
of human activities in and alongside streams, such
as dams, roadways, pastureland, and trash.

Riparian vegetative cover: Vegetation corridor
alongside streams and rivers. Intact riparian
vegetative cover reduces pollution runoff, prevents
streambank erosion, and provides shade, lower
temperatures, food, and habitat for fish and other
aquatic organisms.

Stream order: Stream size, based on the
confluence of one stream with another. First-order
streams are the origin or headwaters. The
confluence or joining of two Ist-order streams
forms a 2nd-order stream, the confluence of two
2nd-order streams forms a 3rd-order stream, and
so on.

Streambed sediments: Fine sediments and silt on
the streambed. In excess quantities, they can fill in
the habitat spaces between stream pebbles,
cobbles, and boulders and suffocate
macroinvertebrates and fish eggs.
Stressors: Factors that adversely effect—and
therefore degrade—aquatic ecosystems. Stressors
may be chemical (e.g., excess nutrients), physical
(e.g., excess sediments on the streambed), or
biological (e.g., competing invasive species).

Taxa: Plural of taxon; groupings of living
organisms, such as phylum, class, order, family,
genus, or species. Scientists organize organisms
into taxa in order to better identify and
understand them.

Transect: A path or line along which one counts
and studies various aspects of a stream, river, or
otner study area.

Wadeable streams: Streams that are small and
shallow enough to  adequately sample by wading,
without a boat.
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                                                   Sources and References
Sources and References
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U.S. EPA (Environmental Protection Agency). 2000. National Water Quality Inventory:
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     Office of Water, Washington, D.C.
USCS  (U.S. Geological Survey). 1999. The Quality of Our Nation's Waters - Nutrients and
     Pesticides.  U.S. Geological Survey Circular 1225. U.S. Department of the Interior,
     U.S. Geological Survey, Reston, VA.
Wohl,  E. 2004. Disconnected Riven — Linking Rivers to Landscapes. Yale University Press,
     New Haven, CT.

Indices of Bio tic Integrity
Barbour, M.T.,  J.B. Stribling, and J.R. Katr.  1995. Multimetric approach for establishing
     biocriteria and measuring biological condition. Chapter 6 In Biological Assessment and
     Criteria: Tools for  Water Resource Planning and Decision Making. Edited by W.S. Davis and
     T.P. Simon. Ecwis Publishers, Boca Raton, FL.
Frey, D.G. 1977. The integrity of water - An historical approach. In The Integrity of Water.
     Edited by S.K. Ballentine and L.J. Guarala. U.S. Environmental Protection Agency,
     Washington, D.C.

Karr, J.R. and D.R. Dudley. 1981. Ecological perspective on water quality goals. Environmental
     Management 5:55-68.

Karr, J.R. 1981. Assessment of biotic integrity using fish communities. Fisheries 6:2]—27.

Observed/Expected Models
Hawkins, C.P. 2006. Quantifying biological  integrity by taxonomic completeness: Evaluation
     of a potential indicator for use in regional- and global-scale assessments. Ecological
     Applications 16:1251 -1266.
Hawkins, C.P,  R.H.  Norris, J.N.  Hogue, and J.W. Feminel'a. 2000. Development and
     evaluation of predictive models for measuring the biological integrity of streams.
     Ecological Applications 10:1456-1477.
Van Sickle, J., C.P. Hawkins, D.P. Larsen, and A.T. Herlihy. 2005. A null model for the
     expected macroinvcrtebrate assembalge in streams. Journal of the North American
     Benthological Society 24:178-1 91.
Wright, J.R 2000. An introduction to RIVPACS. In Assessing the Biological Quality of Fresh
     Waters. Edited by J.F. Wright, D.W Sutcliffe, and M.'i". Furse. Freshwater Biological
     Association, Ambleside, UK.

Physical Habitat
Kaufmann, P.R., P. Levine, E.G. Robison, C. Seeliger, and  D. Peck. 1999. Quantifying Physical
     Habitat in Wadeable Streams. E.PA/620/R-99/003. U.S. Environmental Protection Agency,
     Washington,  D.C.
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                                                    Sources and References

Reference Condition
Bailey, R.C., R.H. Morris, and T.B. Reynoldson. 2004. Bioassessment of Ereshwater Ecosystems:
     Using the Reference Condition Approach. Kluwcr Academic Publishers, New York, NY.
Hughes, R.M. 1995. Defining acceptable biological status by comparing with reference
     conditions. In  Biological Assessment and Criteria: Tools for Water Resource Planning and
     Decision Making for Rivers and Streams. Edited by W. Davis and T. Simon. Lewis
     Publishing, Boca Raton, PL.
Stoddard, J.L., D.P.  Larsen, C.P. Hawkins, R.K.Johnson, and R.H. Norris. 2006. Setting
     expectations for the ecological condition  of running waters: I he concept of reference
     condition. Ecological Applications /6(4):1267-1 276.

Other EMAP Assessments
Stoddard, J.L., D.V. Peck, S.G. Paulsen, J. Vim Sickle, C.P. Hawkins, A.T. Herlihy,
     R.M.  Hughes,  PR. Kaufmann, D.P. Larsen, C. Lomnicky,  A.R. Olsen, S.A. Peterson,
     PL. Ringold, and T.R. Whittier. 2005. An Ecological Assessment of Western Streams and
     Rivers. LPA 620/R-05/005.  U.S. Environmental Protection Agency, Washington, D.C.
Stoddard, J.L., A.T.  Herlihy, B.H. Hill, R.M. Hughes, PR. Kaufmann, D.J. Klcmm, J.M.
     Lazorchak, KH. McCormick, D.V. Peck, S.G. Paulsen,  A.R. Olscn, 13.P. Larsen,  J. Van
     Sickle, and T.R. Whittier. 2006. Mid-Atlantic Integrated Assessment (MAIA) - State of the
     Flowing Waters Report. EPA 620/R-06/001. U.S. Environmental Protection Agency,
     Office of Research and Development, Washington, D.C.
U.S. EPA (Environmental Protection Agency). 2000. Mid-Atlantic Highlands Streams
     Assessment. EPA/903/R-00/01 5. U.S. Environmental Protection Agency, Region  III,
     Philadelphia, PA.

Biological Condition Gradient/Quality of Reference Sites
Davies, S.P. and S.K. Jackson. 2006. The Biological Condition Gradient: A conceptual model
     for interpreting detrimental change in aquatic ecosystems.  Ecological Applications
     76:1251-1 266.
Lattin, P.D. (In Preparation). A process for characterizing watershed Level disturbance using
     orthophotos. Dynamac Corp., Corvallis, OR. (Contact Paul  L. Ringold,
     U.S. Environmental Protection Agency, Corvallis, OR.)

Relative Risk
Van Sickle,  J., J.L. Stoddard, S.G. Paulsen, and A.R. Olsen. 2006. Using relative risk to
     compare the effects of aquatic stressors at a regional scale. Environmental Management
     38(6): 1020-1030.
                                  TheWadeable Streams Assessment A Collaborative Survey of the Nation's Streams

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Sources and References

Nutrients
Bourassa, N.  and A. Cattaneo. 1998. Control of periphyron biomass in Laurentian streams
     (Quebec). Journal of the North American Rentholologica! Society 77:420—429.
Dodds, W.K. and E.B. Welch. 2000. Establishing nutrient criteria in streams. Journal of the North
     American Renthological Society 19(1): 186-196.
Kelly, M.G. 1998. Use of community-based indices to monitor cutrophication in rivers.
     Environmental Conservation 25:22-29.
Kelly, M.G. and B.A.  Whitton. 1995. The trophic diatom index: A new index for monitoring
     eutrophication in rivers. Journal of Applied Phycology 7:433-444.
Miltner,  R.J.  and E.I. Rankin. 1998. Primary nutrients and the biotic  integrity of rivers and
     streams. Freshwater Biology 40:145-158.
Nordin, R.N. 1985. Water Quality Criteria for Nutrients and Algae. Ministry of Water, Land and
     Air Protection, Water Management  Branch,  British Columbia Ministry of the Environment,
     Victoria, British Columbia, Canada.
Pan, Y., R.J. Stevenson, B.H. Hill, A.T. Hcrlihy, and G.B. Collins. 1996. Using diatoms as
     indicators of ecological conditions in lotic systems: A regional assessment. Journal of the
     North American Benthological Society 75:481-495.
Welch, E.B. 1992. Ecological Effects ofWastnvater. 2nd edition. Chapman and  Hall, London,  UK.
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