SEPA
United States
Environmental Protection
Agency
Office of Research and Development
Washington, DC 20460
February 2006
EPA/620/R-06/001
Mid-Atlantic Integrated Assessment (MAIA)
State of the Flowing Waters Report
-------
MID-ATLANTIC INTEGRATED ASSESSMENT (MAIA)
STATE OF THE FLOWING WATERS REPORT
Stoddard, J.L.1, A.T. Herlihy2, B. H. Hill3, R.M. Hughes2, P.R. Kaufmann1, DJ. Klemm4,
J.M. Lazorchak4, F.H. McCormick5, D.V. Peck1, S.G. Paulsen1, A.R. Olsen1, D.P. Larsen1, J.
Van Sickle1, T.R. Whittier5
1 U.S. Environmental Protection Agency
Western Ecology Division
National Health and Environmental Effects Laboratory
Office of Research and Development
200 SW 3 5th Street
Corvallis, OR 97333
2 Department of Fish and Wildlife
Oregon State University
c/o U.S. Environmental Protection Agency
200 SW 3 5th Street
Corvallis, OR 97333
3 U.S. Environmental Protection Agency
Mid-Continent Division
National Health and Environmental Effects Laboratory
Office of Research and Development
6201 Congdon Boulevard
Duluth, Minnesota 55804-2595
4 U.S. Environmental Protection Agency
Environmental Research Center
National Exposure Research Laboratory
Office of Research and Development
26 West Martin Luther King Drive
Cincinnati, OH 45268
5 Dynamac Corp.
c/o U.S. Environmental Protection Agency
200 SW 3 5th Street
Corvallis, OR 97333
-------
NOTICE
The information in this document has been funded wholly or in part by the U. S.
Environmental Protection Agency. It has been subjected to review by the National Health and
Environmental Effects Research Laboratory and approved for publication. Approval does not
signify that the contents reflect the views of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page ii
-------
TABLE OF CONTENTS
Executive Summary v
Foreword 1
Introduction 3
Purpose 3
Stream and River Condition 3
Regional Statistical Surveys 5
The Mid-Atlantic Region 7
Background 7
Ecological Regions 9
Stream Size 13
Ecological Condition 16
Fish Assemblages 17
Macroinvertebrate Assemblages 20
Algal Assemblages 23
Comparison of Fish, Macroinvertebrate, and Algal Scores 23
Stressors in MAIA Flowing Waters 25
Acidification 27
Other Mining Effects 31
Nutrient Enrichment 31
In-Stream Habitat 33
Riparian Habitat 36
Non-Native Fish 37
Summary Ranking of Potential Stressors 43
Geographic Targeting 48
Coastal Plain 49
Piedmont 50
Valleys 51
Ridges 52
North and Central Appalachians 53
Western Appalachians 54
Conclusions and Further Directions 55
Appendix A: Thresholds A-l
Macroinvertebrate Index of Biotic Integrity A-3
Algal Index of Biotic Integrity A-3
Fish Index of Biotic Integrity A-4
Mine Drainage A-5
Acid Mine Drainage A-5
Acid Deposition A-6
Phosphorus A-6
Nitrogen A-6
Excess Sediment A-7
Large Woody Material A-8
Riparian Habitat Condition A-9
Appendix B: Calculating Relative Risk B-l
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page iii
-------
Definition and example calculation B-l
Confidence intervals for Relative Risk B-2
Appendix C: Further Reading C-l
Environmental Monitoring and Assessment Program C-l
Sample Survey Design C-l
Ecological Regions C-2
Biotic Integrity C-2
Stressors C-3
Relative Risk C-4
Other Mid-Atlantic Assessments C-4
Environmental Report Cards C-4
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page iv
-------
LIST OF FIGURES
Figure 1. The MAIA region with sampling sites viii
Figure 2 The Mid-Atlantic Integrated Assessment (MAIA) region 2
Figure 3. The MAIA region with sampling sites 6
Figure 4. Ecological regions (ecoregions) of the Mid-Atlantic region 10
Figure 5. Strahler orders 13
Figure 6. River Continuum Concept 14
Figure 7. Lengths of streamsin different stream orders 15
Figure 8. Distribution of flowing waters with game and non-game fish 16
Figure 9. Fish IBI scores 19
Figure 10. Macroinvertebrate IBI scores 21
Figure 11. Algal IBI scores 22
Figure 12. Land use and land cover 26
Figure 13. Extent of acid deposition effects 28
Figure 14. Extent of acid mine drainage 29
Figure 15. Extent of all mine drainage effects 30
Figure 16. Extent of excess phosphorus concentrations 32
Figure 17. Extent of excess nitrogen concentrations 33
Figure 18. Extent of excess sedimentation 34
Figure 19. Extent of large wood in flowing 35
Figure 20. Extent of problems with riparian condition 37
Figure 21. Relationship between Large Wood and Riparian Condition 38
Figure 22. Extent of non-native fish species 39
Figure 23. Cumulative frequency distribution for the percentage of non-native fish 40
Figure 24. Extent of mercury concentrations 41
Figure 25. Extent of organic contaminants 42
Figure 26. Relative extent of major stressors 43
Figure 27. Relative risk values 45
Figure 28. Comparison of relative extent and relative risk to fish 47
Figure 29. Comparison of relative extent and relative risk to macroinvertebrates 47
Figure 30. Comparison of relative extent and relative risk to algae 48
Figure 31. Summary of Coastal Plain ecoregion condition 49
Figure 32. Summary of Piedmont ecoregion condition 50
Figure 33. Summary of Valley ecoregion condition 51
Figure 34. Summary of Ridge ecoregion condition 52
Figure 35. Summary of North and Central Appalachian ecoregion condition 53
Figure 36. Summary of Western Appalachian ecoregion condition 54
Figure 37. Two subregions that could be targeted for protection efforts—The Ridge and
North/Central Appalachian ecoregions 56
Figure 38. Two subregions that could be targeted for restoration efforts—the Coastal Plain and
Western Appalachian ecoregions 57
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page v
-------
Ml
0 40 80 120 160.
|^^^^^^^E=^^^^^B K Icmeters
The Mid-Atlantic Integrated Assessment (MAIA) region
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page vi
-------
EXECUTIVE SUMMARY
This assessment serves the purpose of a report card on the state of streams and rivers in the
Mid-Atlantic region. It combines data from two sample surveys of flowing waters conducted in
the region by the U.S. Environmental Protection Agency during the period 1993-98 (Figure 1).
Two unique aspects of this assessment are very important: (1) it focuses first on the biological
status of streams and rivers (to assess their ecological condition), and then on the stressors
having both the greatest extent and the greatest effects on biological assemblages; and (2) it
results from a sample survey design that allow us to present the results as though every stream
and river in the region had been sampled. It provides the first statistically unbiased assessment of
the health of the region's flowing waters.
Many will conclude from reading this report that the Mid-Atlantic region is getting a failing
grade. The report relies on newly created Indices of Biotic Integrity (IBIs) to assess ecological
condition. Biotic integrity can be described as "the capacity of an ecosystem to support and
maintain a biota that is comparable to that found in natural conditions." The IBIs developed for
three key biological assemblages in Mid-Atlantic streams and rivers—fish, macroinvertebrates
and algae—all reach similar conclusions, and they are not encouraging. Roughly one-third of the
region's stream length exhibits IBI scores that are classified as 'poor,' and forty percent are
classified as 'marginal,' regardless of which assemblage is used to draw conclusions. Overall,
only one-quarter to one-third of the stream resource of the Mid-Atlantic region exhibits good
biotic integrity.
Biological Assemblage:
Proportion of Stream Resource
in Poor Condition
Primary Stressors *
Fish
Macroinvertebrates
Algae
31%
41%
33%
Non-native fish
Lack of large wood
Excess fine sediments
Acidity
Nutrients
Excess fine sediments
* based on combination of high relative extent and high relative risk to assemblage
What kinds of environmental stressors are associated with poor biotic integrity in the Mid-
Atlantic? The most important stressors are those that share two characteristics: they are relatively
widespread (occurring in a high proportion of stream length) and represent high relative risks to
the biological assemblages (i.e., they are more likely to be found in streams with poor biotic
integrity). When both characteristics are considered, each biological assemblage presents its
own list of key stressors.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page vii
-------
Ecoregions
n Ridge
CD Valley
(HI Western Appalachians
CH North - Central Appalachians
I I Piedmont
d! Coastal Plain
Figure 1. The Mid-Atlantic Integrated Assessment (MAIA) region, and the sampled streams
and rivers used in this report. Shaded background colors illustrate the aggregated ecological
regions used for reporting results in this report.
• For fish: the introduction of non-native fish species (occurring in 47% of the Mid-Atlantic
stream resource) and lack of large woody material (necessary to maintain habitat complexity,
and lacking in 26% of stream length) are both common stressors with high relative risks.
• For macroinvertebrates: the presence of excess fine sediments (occurring in 28% of the Mid-
Atlantic stream resource) is the most common stressor with demonstrable effects on biotic
integrity. Acidity, from either acid rain or acid mine drainage, appears to have significant
deleterious effects on macroinvertebrate integrity when it occurs, but is relatively uncommon
(<5% of stream length in the region).
• For algae: two nutrients, phosphorus and nitrogen, exhibit the highest relative risks of any
stressors on any biological assemblage—both are relatively common in the region (14% to
18% of total stream length). As with macroinvertebrates, poor algal condition is also
associated with excess fine sediments—the relative risk from excess sediments is lower than
for nutrients, but they occur in a larger proportion of the stream resource (28%).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page viii
-------
Not surprisingly, neither ecological condition nor the relative importance of aquatic stressors
is uniform across the Mid-Atlantic region. When monitoring data are analyzed according
ecological regions (ecoregions), two subregions (the Ridge and North/Central Appalachian
ecoregions) are clearly in better overall condition than the others, with more than 40% of the
stream resource in good condition for at least one biological assemblage. Two ecoregions are
clearly more degraded than the others (the Coastal Plain and Western Appalachian ecoregions),
with more than 40% of their total stream length in poor condition for two or more biological
assemblages—in both of these subregions, the assemblage in poorest condition indicates that
more than 50% of the stream resource exhibits poor biotic integrity. In between these two
extremes of ecoregional condition are two subregions in intermediate condition—the Piedmont
and Valley ecoregions; both have more than 40% of their stream resource in poor condition for
one of the biological assemblages.
Ecological Region:
Coastal Plain
Piedmont
Valleys
Ridges
North and Central
Appalachians
Western
Appalachians
Summary of
Condition
Relatively Poor
Intermediate
Intermediate
Relatively Good
Relatively Good
Relatively Poor
Biological Assemblage
Most at Risk
(% of stream length in
poor condition)
Macroinvertebrates
(88%)
Macroinvertebrates
(42%)
Macroinvertebrates
(45%)
Fish
(26%)
Fish
(40%)
Algae
(51%)
Primary Stressors*
Excess sediments
Non-native fish
Non-native fish
Nutrients
Non-native fish
Nutrients
Non-native fish
Lack of large wood
Non-native fish
Lack of large wood
Excess sediment
Lack of large wood
* based on relative extent ofstressor in ecoregion
We cannot assess relative risk to these assemblages at the ecoregion scale, due to insufficient
numbers of sites, but we can determine which environmental stressors are most common in each
ecoregion. An examination of those stressors found in the greatest extent of the stream resource
should help make decisions about which environmental problems merit the greatest attention in
these subregions:
• Ecoregions in relatively poor condition: The Coastal Plain and Western Appalachian
ecoregions have a mix of physical and biological habitat indicators as their most common
stressors. Excess fine sediments are a common stressor in both ecoregions (54% of
stream length in the Coastal Plain, 38% in the Western Appalachians); presence of non-
native fish (Coastal Plain, 55%) and lack of large wood (Western Appalachians, 41%) are
only slightly less common.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page ix
-------
• Ecoregions in intermediate condition: The Piedmont and Valley ecoregions share the
two most common stressors: presence of non-native fish species (69% of the Piedmont
stream resource, 57% in the Valleys) and nutrients (excessive phosphorus is found in
29% of Piedmont stream length, excessive nitrogen is found in 39% of the Valley stream
resource).
• Ecoregions in relatively good condition: The two most common stressors in the Ridge
and North/Central Appalachian ecoregions are identical: presence of non-native fish
species (47% and 32% of stream length, respectively) and lack of large woody material
(25% of the stream resource in both ecoregions).
An assessment of the type presented in this Report presents both a challenge and an
opportunity to regional managers. The challenge is to take this report card, examine it in detail,
and decide how best to improve the condition of the region's flowing waters—by focusing on the
assemblages most at risk, the stressors that pose the greatest relative risks to those assemblages,
and the subregions with the greatest problems (or greatest possibilities for protection). The
opportunity is to use this assessment as a yardstick against which progress can be measured. If
the regulatory actions, restoration and remediation efforts, and management decisions undertaken
in the region are having their intended effect(s), then improvements in ecological condition
should result. It only remains to be seen how effective we can be in improving the condition of
Mid-Atlantic streams and rivers, given the compass that good data, like those presented in this
Report, can provide.
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page x
-------
FOREWORD
This Mid-Atlantic Integrated Assessment (MAIA) "State of the Flowing Waters Report" is
an ecological assessment of non-tidal streams and rivers in the Mid-Atlantic region. It is based
on the combined results of two unique and experimental monitoring programs implemented
through the U.S. EPA's Environmental Monitoring and Assessment Program (EMAP) during the
years 1993-98. We present these results, presented in a way that we hope both environmental
resource managers and the general public find useful, with two major objectives in mind: (1) to
document, in as clear and unbiased a manner as possible, the overall condition of the vast
network of flowing waters that drain the Mid-Atlantic region; and (2) to demonstrate the utility
and flexibility of an EMAP-like approach to environmental monitoring at this regional scale.
The assessment is divided into two major categories. We first document the ecological
condition of streams and rivers in the MAIA region, through the use of direct measures of their
resident biological assemblages (fish, macroinvertebrates and algae). We then assess the relative
importance of a long list of potential stressors on those assemblages, based on direct measures of
their chemical, biological and physical habitat, and human use of the watersheds. We present the
results in this way in order to inform readers about where the major current ecological problems
occur in the region, what the most important threats to the current ecological condition are, and
how much risk these stressors represent to aquatic ecosystems.
Our approach in collecting the data for this assessment has two major characteristics. First,
it focuses as much as possible on direct measures of biological indicators, and on the chemical
and physical properties of stream and rivers that are most likely to have effects on biological
communities. Second, it uses an innovative statistical design that insures that the results are
representative of the region, and allows us to extend this statistical certainty in the results to
smaller areas within the region (e.g., to the major ecological regions within the MAIA region)
where desired.
The report is organized into 5 sections and 2 appendices. After a short Introduction to the
assessment, we describe the geographic diversity of the Mid-Atlantic Region and its streams
and rivers. In Section 3 we present the results of sampling of the Ecological Condition of
MAIA Flowing Waters, and in Section 4 we expand these results to include the relative
importance of Stressors in MAIA Flowing Waters. Finally, we discuss how stream managers
in the Mid-Atlantic might use the results of this assessment for Geographic Targeting.
This report is written for the public, for environmental managers, and for decision-makers.
Much of the technical background for the report has already been published in the scientific
literature, and we include a list of key publications in Appendix C at the back of the report.
Readers who wish to learn more about the design, specific indicators, or other elements of the
assessment are encouraged to consult this list and read the technical papers upon which this
assessment is based.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
-------
Ml
0 40 80 120 160.
|^^^^^^^E=^^^^^B K Icmeters
Figure 2 The Mid-Atlantic Integrated Assessment (MAIA) region
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 2
-------
INTRODUCTION
PURPOSE
The Mid-Atlantic Integrated Assessment (MAIA) Flowing Waters Assessment has a four-
fold purpose:
1) Assess and report on the ecological condition of all flowing waters in the Mid-Atlantic
region.
2) Use direct measures of biological assemblages to describe the ecological condition of
MAIA streams and rivers.
3) Use supplemental measures of chemical, physical and biological habitat to identify and
rank the relative importance of potential stressors affecting stream and river condition.
4) Influence how states design their monitoring programs, how they assess and report on the
condition of flowing waters.
Working in partnership with the states (Delaware, Maryland, New Jersey, North Carolina,
Pennsylvania, Virginia, and West Virginia), the U.S. Fish and Wildlife Service (USFWS), U.S.
Geological Survey (USGS), multiple universities, and Environmental Protection Agency (EPA)
Region III, the EPA Environmental Monitoring and Assessment Program (EMAP) assembled
crews in 1993 through 1998 to collect 1050 samples on 850 sites throughout the Mid-Atlantic
region, including both wadeable streams and boatable rivers. All of the crews were trained to use
identical sampling methods to facilitate comparisons across the region. This report explains our
objectives, methods and results.
STREAM AND RIVER CONDITION
Most historic assessments of stream quality have focused on describing the chemical quality
of streams and, occasionally, on sport fisheries impacts. As we have made progress in controlling
chemical problems, it has become obvious that the ultimate concern is actually the health of the
plants and animals that inhabit these streams and rivers.
In this assessment we have tried to address this concern not by ignoring physical and
chemical measurements, but by shifting the focus to direct measurements of the biota
themselves. In this assessment, the ecological condition of flowing waters is defined by
biological indicators. The biological organisms in a stream integrate the many physical and
chemical stressors and forces, including other biota (parasites, predators, or competitors), that are
acting in, and on, the stream ecosystem. Stream and river condition can be determined by
assessing appropriate biological indicators (Table 1), or combinations of these indicators called
indices. Information on the ecological condition of flowing waters is supplemented by
measurements of other stream characteristics, especially those physical, chemical, or other
biological factors that might influence or affect stream condition. These stream characteristics
allow us to assess the potential stressors of stream condition, based on expected signals from
major environmental perturbations (e.g., physical habitat modification, mine drainage, acid rain,
agricultural nutrients, etc.).
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 3
-------
Table 1
Examples of ecological indicators measured in MAIA streams and rivers
Indicators of Ecological Condition Rationale
Fish assemblages
Macroinvertebrate assemblages
Algal assemblages
Important indicators of stream and river condition; respond strongly
to larger-scale disturbances in streams and watersheds, including
channelization and riparian disturbance; middle to upper end of food
web; accumulate contaminants that are then consumed by mammals
and birds. Caution: some smaller streams may naturally lack fish.
Absence offish from small streams cannot be interpreted as an
indicator of poor ecological condition.
Larval stages of macroinvertebrates (largely aquatic insects; also
snails and some worms) are sensitive to disturbances to stream
chemistry and in-stream habitat (particularly sedimentation).
Because many adult stages are mobile, macroinvertebrate
assemblages are thought to recover rapidly after conditions improve.
Attached algae (largely diatoms) grow on surfaces of rocks and fine
substrates (e.g., sand) and are very sensitive to changes in chemistry
(particularly nutrients and pH) and sedimentation; most species are
cosmopolitan (occur throughout the world) and their environmental
tolerances are therefore well known.
Indicators of Stress
Acidity
Nutrients
In-stream habitat
Riparian habitat
Rationale
Low values of pH and alkalinity result from both acid rain and acid
mine drainage; can be directly or indirectly toxic (e.g., by
mobilizing toxic metals) to fish and macro-invertebrates; leads to
greatly simplified biological assemblages.
Excess amounts of phosphorus and nitrogen enter streams from
fertilizer use and sewage; stimulate algal growth and simplify
biological assemblages.
Excess supplies of fine sediments from watersheds fill spaces
between gravels, cobbles and boulders that are normal habitat for
macroinvertebrates and spawning fish; sediment movement
downstream disturbs attached algae. Large wood (formerly Large
Woody Debris) provides in-stream habitat complexity required for
high biodiversity, and helps to stabilize fine sediments.
Stream bank alteration (removal of trees, shrubs, grasses; erosion of
banks; stabilization of banks) affects shading and habitat complexity
of streams.
The combination of biological and stressor indicators listed in Table 1 represents our best current
understanding of the biological, physical and chemical factors that collectively determine stream
and river quality. Many of the in-stream stressors listed have a direct impact on biological
assemblages, and are in turn affected by human use and disturbance of the upstream landscape.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 4
-------
One of the unique aspects of this assessment is that it uses data from two statistical surveys
(see below) of streams and rivers to describe the condition and characteristics of the population
of flowing waters in the Mid-Atlantic region. It is intended to answer, in as direct and unbiased a
way as possible, the question, "What is the condition of Mid-Atlantic streams and rivers?"
REGIONAL STATISTICAL SURVEYS
In the past, EPA and the states addressed municipal and industrial point sources of
chemicals as major threats to streams and rivers. This led to focusing monitoring, assessments,
and controls very locally on individual segments of streams above and below known point source
discharges. Monitoring locations were selected to evaluate the effectiveness of improved
treatment of these municipal and industrial discharges. As these point sources were cleaned up, it
became apparent that additional stressors were threatening our aquatic resources. Some attempts
were made to aggregate existing data and use them in regional assessments, but the limitations of
this approach became apparent because the local sites were not representative of other flowing
waters or areas in the region, and consistent sampling and analysis methods were rarely used.
Another approach was needed to assess stream quality on a regional basis.
EPA and the states, working first on small streams in the Mid-Atlantic Highlands, and later
expanding to both rivers and streams throughout the Mid-Atlantic region, wrestled with these
problems and came up with a different approach for stream/river monitoring. In addition to
implementing direct measures of the ecological condition of the biota themselves, they devised a
way to pick monitoring locations that do not focus on known problem areas (e.g., sewage
outfalls). Instead, monitoring sites were chosen through a statistical approach that provides, in
aggregate, a clear and objective view of the condition of all flowing waters. It is hoped that this
approach, and this assessment, can serve as models for future National Water Quality
Inventories. These biennial reports (also known as 305[b] reports, after the section of the Act that
mandates them), to Congress are required by the Clean Water Act, and are often criticized for
their lack of objectivity.
During the years 1993 and 1994, EPA researchers used sample survey techniques to identify
representative small streams (1st through 3rd order) throughout the upland portions of the Mid-
Atlantic region. The biological, chemical and physical habitat sampling of those streams resulted
in the Mid-Atlantic Highlands Streams Assessment (see Appendix C), the first comprehensive
assessment of the ecological condition of streams in any region using both statistical site
selection and biological indicators. Work in the Highlands (referred to as MAHA) continued in
1995 and 1996, and those additional data are used in this report.
In 1997 and 1998, data collection was expanded to all non-tidal streams of the Mid-Atlantic
region (Figures 2 and 3), and for the first time the unique aspects of EMAP sampling (biological
indicators and statistical design) were extended to include large (non-tidal) rivers. This larger-
scale project was known as MAIA. A major emphasis in MAIA was to extend the sampling
methods developed for wadeable streams in MAHA to the large rivers included in MAIA. The
result is a set of sampling protocols, all based on identical principles and producing identical
information, for all sizes of flowing waters (see Lazorchak references in Appendix C).
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 5
-------
Ecoregions
d Ridge
alley
D Western Appalachians
I I North - Central Appalachians
C] Piedmont
O Coastal Plain
Figure 3. The MAIA region with sampling sites on small upland streams (open circles,
sampled as part of the MAHA project), small regional streams (grey circles, sampled as part
of MAIA) and large rivers (black circles, MAIA).
Because of the unique statistical properties of the EMAP sample surveys, we are able to
combine results from both MAHA and MAIA in this assessment, and produce unbiased
estimates of the condition of all flowing waters in the Mid-Atlantic region for the period from
1993 to 1998. In total, the MAHA and MAIA projects collected 1050 samples on 850 sites in the
region. These data are used to estimate such regional characteristics as the proportion of stream
miles that are impaired or degraded biologically, the relative importance of potential stressors
(such as mine drainage or stream sedimentation) in the region, and the relative risk that these
stressors pose to biological assemblages.
A statistical survey of flowing waters operates in the same manner as the public opinion
polls used to project winners and losers of political elections. A sample of stream reaches is
selected at random to represent the population of flowing waters in a region, just as the sample of
individuals in a public opinion poll is selected to represent the voting population as a whole.
Regional statistical surveys have been used for many years in forestry and agricultural
monitoring programs to determine the condition of forests and agricultural lands, but their use in
assessments of aquatic ecosystems is just beginning. Additional information on the EMAP
stream design can be found in the references listed in Appendix C.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 6
-------
One of the advantages of a regional statistical survey is that, for any estimate of stream and
river condition (e.g., the proportion of stream length in degraded condition), we can also estimate
"confidence intervals" around the estimate. Confidence intervals are measures of uncertainty,
and are exactly analogous to the "margins of error" that accompany public opinion polls (e.g.,
Candidate A leads Candidate B by 10%, with a margin of error of ± 4%—meaning that the true
lead is somewhere between 6% and 14%). These margins of error are smaller when we use larger
sample sizes (e.g., the number of people taking part in a poll, or the number of flowing waters
sampled), and are smaller when our population estimates are near one of the extremes (e.g., near
1% or 99%). The greatest uncertainty occurs when the sample size is small (e.g., fewer than 50
sites) and the population estimate is near 50%—analogous to a dead heat in a political poll.
Because the number of sites sampled in MAHA and MAIA varies with different indicators (the
largest number of sites have chemical data; the smallest number of sites have fish data) and the
regions or sub-regions assessed (e.g., the MAIA region as a whole has the highest number of
sites; the Coastal Plain ecoregion has the lowest number), the confidence intervals are slightly
different for each estimate of condition that we present. Rather than cluttering the report with
hundreds of confidence intervals, we have chosen to present a single, general "margin of error"
for each indicator and each subregion assessed. Each estimated margin of error is the 90%
confidence interval calculated from the actual sample size for each estimate, but assuming a
population estimate of 50% across the board. Readers of this report may want to keep these
confidence intervals in mind as they contemplate the results (e.g. given a margin of error of plus
or minus 15%, are apparent differences between subregions significant?).
THE MID-ATLANTIC REGION
BACKGROUND
The Mid-Atlantic region encompasses approximately 180,000 square miles and extends
from the Atlantic Ocean in the east to the Ohio River in the west, and from the headwaters of the
Delaware and Susquehanna drainages in New York in the north to the Neuse River drainage in
North Carolina in the south (Figure 2). It includes all of EPA's Region III, all of the states of
Delaware, Maryland, Pennsylvania, Virginia and West Virginia, and parts of New Jersey, New
York and North Carolina.
The Mid-Atlantic region is a diverse
place with dramatic changes in geology,
elevation, climate, vegetation, land cover
and demographics. These characteristics
work together to create interesting
patterns in the landscape. It is helpful to
consider these patterns, because they
provide a context to discuss and
understand the health of the region's
rivers and streams.
To the east, the low-lying, flat Coastal
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page?
-------
Plain is characterized by many shallow inland bays and meandering tidal rivers. Chesapeake
Bay, the nation's largest estuary, dominates the landscape and provides both commercial and
recreational opportunities to millions of people. Agriculture is the dominant land cover on the
Delmarva peninsula and the eastern shore of Maryland. This area has the smallest amounts of
forested land cover in the region.
Most of the people in the Mid-Atlantic region live in the urban corridor between the
District of Columbia and Philadelphia, and in the Pittsburgh area. Population growth is highest in
the Coastal Plain, near the ocean and the estuaries; growth is flat or negative in the western areas
of the region. Historically, people have settled where rich farmland and navigable rivers offer
abundant food and easy transportation. Philadelphia is located on the Delaware River; Harrisburg
on the Susquehanna River; Pittsburgh on the Ohio, Allegheny and Monongahela Rivers;
Baltimore on the Patapsco River; Washington, D.C. on the Potomac River; Richmond on the
James River; and Norfolk directly on the Chesapeake Bay.
As one travels west across the region, the low, rolling hills of the Piedmont appear. These
hills are like stair steps leading to the Blue Ridge and the Appalachian Mountains farther west.
The Blue Ridge Mountains form the first barrier to the western landscape. They appear as a
sharp, forested ridge. Once beyond that ridge, the Great Valley of the Shenandoah opens up.
Farmland once again dominates the landscape. These fertile soils have been farmed for centuries.
Continuing westward, the Appalachian Ridge and Valley province appears, with sharp-
crested ridges running from northeast to southwest in clean parallel lines like long waves on an
ocean. These ridges were formed by the folding of the landscape, and the road cuts offer
excellent opportunities to view the deformed layers of sedimentary rocks. As one might expect,
the ridges of this region remain largely forested. The slopes are steep, the soils are thin, and they
are not ideal for either farming or urban development. The valleys of the Ridge and Valley
Province are intensively farmed. The landscape is fairly flat in the valleys, and the soil is deep
and fertile.
Farther to the west and south, the Allegheny
Escarpment rises abruptly. At the top of this
escarpment, the layers of sedimentary rock lie
relatively flat and undisturbed. This is the
Allegheny Plateau. Unlike the long, broad, parallel
valleys and ridges to the east, the creeks and rivers
here dissect the flat plateau to form deep and
twisting gorges. The valley bottoms are much
narrower than those to the east.
The largest tracts of forest in the Region are found on the Plateau, to the north in
Pennsylvania, and to the south in West Virginia. Some of these forests are the largest tracts of
public land in the region and offer significant recreational opportunities to hikers, hunters,
fisherman, and others. In the Mid-Atlantic region, many of these forested areas remain forested
because they have steep slopes with poor soils that are unsuitable for agriculture and urban
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 8
-------
development. These characteristics make the areas more susceptible to the effects of acid rain.
Portions of the Allegheny Plateau and Ridges are particularly sensitive to acid rain.
The Western Allegheny Plateau and Central Appalachians are made up of bedrock
containing significant amounts of coal. Bituminous coal fields, where high sulfur coal is found,
are found primarily in the West—western Maryland, western Virginia, Pennsylvania and
northern West Virginia—and can cause significant acid mine drainage problems when mined.
Lower sulfur, cleaner burning coal is found farther south in southern West Virginia. Much of the
mining activity in recent years has shifted south to extract the lower sulfur coal as a result of
tightening clean air regulations. This coal is often mined by the "valley fill" process which
removes whole mountain tops to reach the coal-bearing strata, and fills adjacent river valley with
spoils. Nearly all of the anthracite coal in the United States is found in eastern Pennsylvania.
Anthracite coal is found folded in discrete layers between layers of sandstone, and results from
the great deformation and movement of rock that produced the Allegheny mountains.
These regional patterns provide important context for understanding the health of rivers
and streams at a broad regional scale. Streams in the valleys and on the Delmarva Peninsula,
with intense agricultural land use, might have higher nutrient, pesticide and bacteria
concentrations and problems with sedimentation. Streams and rivers in the highly urbanized
areas might be impaired by point source and storm water runoff. Streams on the forested ridges
and in the low-lying southern Piedmont and Coastal Plain areas that have naturally low buffering
capacity might be impaired by acid rain. Streams in the coal mining areas of the region might
suffer from acid mine drainage, increased metals and sediment, and larger scale habitat impacts
that result from mining. These patterns only indicate the potential impacts and stressors. We
must take a step further and consider data on stream ecological health, water quality and physical
habitat quality to determine whether actual impacts exist.
ECOLOGICAL REGIONS
Ecological regions (or ecoregions) are areas that have similar soils, vegetation, climate, and
physical geography. An ecoregion perspective highlights the differences, for example, between
mountain areas with their steep slopes, shallow soils, and cooler climate, and valley areas that are
relatively flat, have deep soils, and warmer temperatures; ecoregions permit us to have different
expectations of flowing waters in these very different areas. An ecoregion perspective also helps
us understand why streams respond to various human disturbances as they do and which
management solutions might be applicable. Ecoregional differences play a major role in
determining which flowing waters have been affected by, or are susceptible to, different
stressors. Management practices within an ecoregion typically are applicable for many of the
flowing waters with similar problems because the characteristics of the streams in the ecoregion
are similar.
Ecoregions have been developed at many different scales for the entire U.S., and for smaller
regions like the Mid-Atlantic. For the purposes of this assessment, we have combined various
levels of ecological regions into the six ecoregions described in the next section. We feel these
ecoregions do a good job of capturing the intra-regional variability of the Mid-Atlantic. They
include the: (1) Coastal Plain; (2) Piedmont; (3) Valleys; (4) Ridges; (5) North and Central
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 9
-------
Appalachians; and (6) Western Appalachians (Figure 4). A more complete description of
ecoregions can be found in the references of Omernik and Woods in Appendix C.
Ecoregions
CH Ridge
n Valley
CH Western Appalachians
CH North - Central Appalachians
I I Piedmont
CH CoastafPlain
Figure 4. Ecological regions (ecoregions) of the Mid-Atlantic region. Ecoregions are areas
with similar physical geography, soils, climate and vegetation types. We use six aggregated
ecoregions to classify and assess stream sites in this report.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 10
-------
COASTAL PLAIN ECOREGION
For the purposes of this assessment, the
"Coastal Plain" comprises both the Middle
Atlantic Coastal Plain ecoregion and the
Southeastern Plain ecoregion. It consists of
low elevation flat plains, with many
swamps, marshes, and estuaries to the east,
and a mosaic of cropland, pasture,
woodland, and forest to the west. It
contains many of the urban centers of the
Mid-Atlantic region, including Washington
D.C., Baltimore and Richmond. Forest
cover in the region is predominantly
longleaf and shortleaf pine, with smaller
areas of oak, hickory, gum, and cypress near major streams. Poorly drained soils are common.
Elevations and relief are generally less than in much of the Piedmont. Streams in this area are
relatively low-gradient and sandy-bottomed.
PIEDMONT ECOREGION
The "Piedmont" (for the purposes of this
assessment) consists of both the Piedmont
ecoregion proper, and the Northern Piedmont
ecoregion—physiographers consider it the non-
mountainous portion of the old Appalachian
highlands. It comprises a transitional area between
the mostly mountainous ecoregions of the
Appalachians to the northwest and the relatively
flat Coastal Plain to the southeast. It is a complex
mosaic of metamorphic, igneous and sedimentary
rocks, with finer-textured soils than in Coastal
Plain. Once largely cultivated, much of this region has reverted to pine and hardwood
woodlands, and more recently has seen increasing conversion to urban and suburban landuse.
VALLEY ECOREGION
The Valley ecoregion, including the "Great Valley," extends
from eastern Pennsylvania southwesterly through southwestern
Virginia. The valleys generally fall into two types, those
underlain by limestone and those with shale. The nutrient rich
limestone valleys contain productive agricultural land. By
contrast, the shale valleys are generally less productive, more
irregular, and have greater densities of flowing waters. Most of
the streams in the limestone valleys are colder and flow all year,
whereas those in the shale valleys tend to lack flow in dry
periods. Dense concentrations of poultry operations can be found
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 11
-------
in many parts of the valleys. Many of the flowing waters in this report are located in the Valley
ecoregion, but drain watersheds that extend onto the Ridges. Most ecological classifications
combine the Valleys and Ridges into a single ecoregion.
RIDGE ECOREGION
The Ridge and Blue Ridge ecoregion is a
series of linear mountainous ridges, with
elevations from approximately 1,000 feet
to 5,700 feet, running between lower
elevation valleys. This mostly forested
ecoregion contains high gradient, cool,
clear streams occurring over mostly
sandstone and shale bottoms. The
ecoregion has no major urban areas and
has a low population density. However,
due in large part to the close proximity of
metropolitan areas in the Coastal Plain and
Piedmont regions to the east, recreational development in the region has increased considerably
in recent years.
NORTH AND CENTRAL APPALACHIAN ECOREGION
The North and Central Appalachians in
northern and central Pennsylvania and
central West Virginia are a vast elevated
plateau of high hills, open valleys, and low
mountains with sandstone, siltstone, and
shale geology, and coal deposits. The
northern and eastern portions of this
ecoregion are the only glaciated areas in this
Report. Much of the eastern part of the
ecoregion is farmed and in pasture, with hay
and grain for dairy cattle being the principal
crops. There also are large areas in oak and
northern hardwood forests. Land use activities are generally tied to forestry and recreation, but
some coal and gas extraction occurs in the northwestern part of the region.
The southern part of the ecoregion in West Virginia is primarily a forested plateau
composed of sandstone and shale geology and coal deposits. Due to the rugged terrain, cool
climate, and infertile soils, this area is more forested and contains much less agriculture than the
Valley and Western Appalachian ecoregions. Coal mining is a major industry in this part of the
region. Acid mine drainage and stream sedimentation associated with coal mining are possible
stream impacts.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 12
-------
WESTERN APPALACHIAN ECOREGION
The Western Appalachian ecoregion runs
from western Pennsylvania into western West
Virginia. The hilly and wooded terrain of this
ecoregion is less rugged and not as forested as
the ecoregions to the east (North and Central
Appalachians). Much of this region has been
mined for bituminous coal. Once covered by a
maple-beech-birch forest, this region is now
largely in farms, many of which are dairy
operations. This ecoregion is characterized by
low rounded hills, low gradient streams and
extensive areas of wetlands.
STREAM SIZE
Along with ecoregional differences, and differing amounts of human disturbance, potential
stream condition is strongly affected by stream size. In order to standardize the concept of stream
size when comparing streams across large areas, stream sizes are often broken up into Strahler
orders (Figure 5). This is a convenient, and consistent, approach to classifying streams according
to size, with headwater streams (throughout the world) being classified as first order, and larger
orders referring to larger streams. For the EMAP data collection effort In the Mid-Atlantic,
where 1:100,000 scale U.S.G.S. maps were used to specify the stream network, the largest rivers
are eighth order.
Figure 5. Stream sizes are categorized by Strahler orders, demonstrated here for a
hypothetical watershed in the Mid-Atlantic. The confluence (joining) of two 1s* order
streams forms a 2nd order stream; the confluence of two 2nd order streams forms a 3rd order
stream, etc.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 13
-------
The size (or order) of a stream not only affects its natural characteristics, but also its
capacity to handle both point source and non-point source pollutants (Figure 6). Stream size
frequently affects the size and type of biotic community present, particularly for fish, and may
control the relative importance of factors to which the biota respond. Very small streams (first-
order, headwater streams) are often quite clear and shaded by trees; they are likely to be
dominated by aquatic insects in the stream bottom and with small fish that feed on these bottom
organisms. Large streams (sixth- to seventh-order rivers) are often muddy with canopy cover
only along the banks, and are dominated by larger fish that are omnivorous (feeding on plants
and animals) and/or piscivorous (feeding on smaller fish).
shredders
1 I-
wZ. IM^K. w~x}
^^^ ^^^^^t^ ^r i *
peri phy ton I
• .»•- i.4"
10
11
12
collectors
smallmouth
bass
shredders
predators
vascular
hydrophytes
_ catfish
*» J&{
b^.;. -/ V
-^ • p- predators
L /
Relative Channel Width
Figure 6. Stream characteristics change as the size or order of the stream increases. Smaller
streams (1s* through 3rd order) dominate in the region. This "State of the Flowing Waters
Assessment" includes sites throughout the range of stream orders illustrated.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 14
-------
Small, first-order streams are the dominant stream class in the Mid-Atlantic region and
throughout the world; over 125,000 stream kilometers (i.e., almost 60% of the total length) are
classified as first-order streams (Figure 7). Second-order streams are larger and start at the point
where two first-order streams come together. Over 35,000 kilometers of streams in the Mid-
Atlantic (i.e., 17%) are second-order streams. Almost 90% (199,000 km) of flowing waters in the
region are small first- through third-order streams. Because small streams contribute most of the
stream length, their condition has a dominant effect on any assessment that presents its results on
the basis of stream length (like this one, and the National Water Quality Inventories required by
the Clean Water Act).
Historically, management practices have focused on large streams, which are best known to
the public due to their use in navigation and boating, and their visibility from major road
crossings. Small streams, on the other hand, dominate the total stream length in the region,
contribute to the quality and condition of larger streams and rivers, and are critical to
determining the condition of all flowing waters in the Mid-Atlantic.
The stream network used for selecting sampling sites in this assessment, and for estimating
the total length of flowing waters in the region, was the EPA River Reach File, Version 3. This
digital database includes all flowing waters that are represented on USGS maps at a scale of
1:100,000. The map scale used is important because it affects the estimate of stream length and
stream order. The stream network shown on 1:100,000 scale maps was considered a good
representation of the population of Mid-Atlantic flowing waters—official estimates of stream
length (e.g., in each state) by EPA's Office of Water are based on this map scale.
Total Stream Length (km)
0 25000 50000 75000 100000 125000
10 20 30 40 50
Percent of Stream Length
Figure 7. Lengths of streams (both in km and as a percentage of the total) in different stream
orders in the Mid-Atlantic region. Almost 90% of the region's stream length is in small first-
through third-order streams. Large rivers (fifth- through eighth-order) make up about 5%
of the total length of flowing waters.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 15
-------
ECOLOGICAL CONDITION
To assess the overall condition of MAIA flowing waters, we looked at multiple biological,
chemical and physical habitat indicators. To answer the specific question "What is the
ecological condition of Mid-Atlantic streams and rivers? " we rely on direct measures of the
biological communities that inhabit the streams and rivers. Throughout this report, ecological
condition—good, marginal, or poor—is determined by biological indicator or index scores. The
fish, algae, aquatic insects, and other animals and plants in a stream serve as "integrators" of the
multiple stressors to which they are exposed. The biota respond to the cumulative effects of
chemical contaminants, modification of their physical habitat, and changes in both the amount
and the timing of the flow of water.
Game and Non-Game Fish
Non-Game
Fish Only
No
Fish
0 20000 40000 60000 80000 100000 120000
Total Stream Length (km)
Figure 8. Distribution of flowing waters with game and non-game fish, non-game fish alone,
and no fish, across the range of stream orders in the Mid-Atlantic. Small streams, especially
first-order streams, are a very important resource for both game and non-game fish species.
Historically, game fish have been the primary biotic component of interest to the public, and
an emphasis has been placed on the condition of game fisheries in larger rivers. This emphasis
on game fish and large rivers has resulted in a narrow, incomplete view of the status of Mid-
Atlantic flowing waters, where large rivers make up only about 5% of the total stream length.
Some people have defended this large river/game fish perspective by claiming that small streams
do not support fish. While it is true that a much larger proportion of small streams lack fish than
larger streams, small streams are nonetheless an important resource for fish (Figure 8). There are
more than 120,000 kilometers of streams in the Mid-Atlantic with game fish, roughly half
(58,000 km) are first-order streams, while only 9% (10,600 km) are fifth-order and larger rivers.
If both game fish and non-game fish are considered, 54% of the stream length with fish present is
in first-order streams, and 6% in fifth-order and larger rivers (of course, a conclusion based on
water volume would be much different).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 16
-------
By sampling multiple biological assemblages (fish, macroinvertebrates and algae)
throughout the Mid-Atlantic, we have the opportunity to move beyond a narrow, game fisheries
focus, and look instead at the biological integrity of stream and river ecosystems. Biotic
integrity has been defined by Jim Karr (a leading proponent of the concept) as, "the ability to
support and maintain a balanced, integrated, and adaptive community of organisms having a
species composition, diversity and functional organization comparable to those of natural
habitats within a region." Most people would agree that maintaining the biotic integrity of
flowing waters—also a stipulation of the Clean Water Act—is a laudable goal. This assessment
is one of the first steps toward achieving that goal.
FISH ASSEMBLAGES
Streams and rivers must meet a number of requirements if they are to support healthy fish
assemblages—providing a sufficient variety of foods and spawning areas, and a habitat with
diverse forms offish cover, among others. The fish data collected in MAHA and MAIA include
a list of the species found at each site, and a measure of their relative abundances. These data
allow us to calculate a number of characteristics, or metrics, for the fish assemblages—for
example, the total number of species, the number of native species, the number and proportion of
pollution tolerant and intolerant species, etc. The best of these metrics (i.e., those that are
repeatable, responsive to human disturbance), and that contain the most information about the
health of the fish assemblages) have been combined into an overall Index of Biotic Integrity
(IBI), whose values range from 0 to 100 (more information on the fish IBI is listed in Appendix
A). Our assessments of ecological condition (i.e., for fish, macroinvertebrates and algae) are all
based on similarly constructed IBIs.
The critical step in the process of developing a fish IBI is the setting of expectations for
each metric used (e.g., How many native species do we expect to find? How many benthic
species? How many intolerant species?), and for the final IBI. When dealing with a region as
large and diverse as the Mid-Atlantic, the setting of expectations takes on a critical role in
determining the validity of our assessment. We need to know if the expected number of native
species, for example, changes as we move from one ecoregion to another (it does), or from small
streams to large streams (as it also does). In order to set expectations, EMAP relies on estimates
of reference condition (see box). Conceptually, the idea of a reference condition for flowing
waters is simple—it is the condition of streams (and particularly their biota) in the absence of
significant human alteration or degradation. In practice, the concept of reference condition
becomes much more muddy—how much human alteration is "significant", is it equivalent to
"pristine" condition, what do we do in areas where all streams have been degraded to some
degree—and numerous methods have been developed to estimate it. For this assessment, we
have chosen to use a reference site approach, where the least disturbed sites in each ecoregion
(and across a range of stream sizes) were sampled and their data used as estimates of reference
condition. Alternative approaches include the use of historical data (where available), best
professional judgment, and models.
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 17
-------
What is Reference Condition?
The concept of establishing reference conditions is relatively simple—we want to know what sorts of conditions
we would find in streams and rivers in the absence of any significant human disturbance. In practice, reference
condition is much more complicated. There exist multiple definitions of the term "reference condition" - each has
merit and each has some historical precedent. For example, each of following categories (and definitions) of
reference condition are being used in various monitoring and assessment programs today:
Minimally Disturbed Condition (MDC) - this term describes the condition of streams in the absence of
significant human disturbance, and is probably the best approximation or estimate of biotic integrity. One important
aspect of MDC is the recognition that some natural variability in indicators will always occur, and this needs to be
taken into account when describing MDC. Long-term climatic, geologic and ecological fluctuations will inevitably
change the characteristics of individual sites, but the regional range of MDC should be nearly invariant, and its
distribution can serve as an anchor by which to judge current condition. It may serve as a benchmark against which
all other definitions of reference condition can be compared.
Least Disturbed Condition (LDC) - this condition is found in conjunction with the best available physical,
chemical and biological habitat conditions given today's state of the landscape. It is ideally defined by a set of explicit
criteria to which all reference sites must adhere. These criteria will vary from region to region, and are developed
iteratively with the goal of establishing the minimum amount of ambient human disturbance in the region under study.
The specifics of these criteria will vary across ecoregions, as ecological characteristics of the landscape, and human use
of the landscape, vary. Because the condition of the environment changes over time, as either degradation or restoration
proceeds, LDC may vary with time. As the ecological condition of the very best available sites changes through time, so
will our measure of LDC.
Best Attainable Condition BAG) - this is equivalent to the expected ecological condition of least disturbed sites if
the best possible management practices were in use for some period of time. Sites in BAG would be places where the
impact on biota of inevitable land use is minimized. This is a somewhat theoretical condition predicted by the
convergence of management goals, best available technology, prevailing use of the landscape, and public commitment
to achieving environmental goals. The upper and lower limits on BAG are set by the definitions of MDC and LDC
respectively (Figure 2). It is unlikely that it will ever be "better" than MDC, nor "worse" than LDC, but may be
equivalent to either, depending on the prevailing level of human disturbance in a region. As is the case with LDC, BAG
is not invariant, because all of the factors influencing it (e.g., available technology, public commitment) will vary over
time.
Ideally, we would like to know how our estimates of stream condition would change if we were to adopt each of
these alternative views of reference condition, but this is often not possible. The lack of historical data for any
biological assemblage other than fish makes the estimation of historical condition, and therefore any estimation of
Minimally Disturbed Condition, very difficult. Estimates of Best Attainable Condition cannot currently be made with
real data—they rely on best professional judgment—and are therefore open to criticisms about their validity and
potential for bias.
The Environmental Monitoring and Assessment Program (EMAP) approach to reference condition (used in this
assessment) is to rely on the "Least Disturbed Condition" definition, and to use data from sites that meet the least-
disturbed criteria to estimate reference condition. As we adopt this definition, we need also to recognize that the
"Least Disturbed Condition," in today's world, may be considerably disturbed.
One important aspect of the EMAP approach is that the reference state (i.e., whether an individual site is in
reference condition) is defined by the condition of the physical, chemical and biological habitat, and not by the
biological assemblages themselves. This avoids some of the circularity (e.g., using biological data to define reference
sites for use in interpreting those same biological data) that can permeate the process of estimating reference
condition. Once the sub-population of sites that meet pre-identified criteria is identified, then the biological metric or
ecological index scores measured at those sites can be used to define the distribution of biological reference
conditions for the region (see "Setting Expectations" box, and Appendix A).
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 18
-------
In the Mid-Atlantic region as a whole, 21% of the total stream length would be considered
to have fish assemblages in good condition (Figure 9) that is, their IBI scores indicate biotic
integrity similar to the upper 75% of reference sites. A larger proportion of stream length, 31%,
has fish assemblages in poor condition, and the largest proportion, 42%, are in marginal
condition. Importantly, we could not calculate IBI scores for about 6% of the Mid-Atlantic
stream length, because all of these streams drain very small watersheds (i.e., less than two square
kilometers) and contained too few fish when sampled. Because of their small size, we are unable
to determine whether the low numbers offish is due to anthropogenic or natural causes, and they
are left out of the estimates of stream condition based on fish (Figure 9).
MAIA Region Overall
margin of error ± 5%
....?• -&--<,
Nortii-Convat
Appalachians
Piedmont
margin of err or ±
Fish Biotic Integrity
• Good
O Marginal
• Poor
O Insufficient data
Figure 9. Fish IBI scores in Mid-Atlantic flowing waters, and the proportion of the total
stream length in good, marginal and poor condition. Red, yellow and green markers on the
map indicate the locations of individual sites that contribute to the estimates of stream
length in each condition. About 31% of the Mid-Atlantic stream length has fish assemblages
in poor condition. Roughly 6% of stream sites had few or no fish, but were located in
watersheds too small for us to determine reliably whether they should be expected to have
fish. Of the six ecological regions, the Coastal Plain ecoregion has the highest proportions of
stream length in poor condition (44%).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 19
-------
Not surprisingly, sites with poor biotic integrity for fish are not evenly distributed in the six
ecoregions of the Mid-Atlantic (Figure 9). The Coastal Plain has the highest proportion in poor
condition (44%), followed by the North and Central Appalachians (40%) and the Valley
ecoregion (33%). The Piedmont ecoregion has a relatively small proportion of stream length in
poor condition (20%), and almost 80% in either good or marginal condition. The ecoregion with
the largest proportion in good condition is the Ridge ecoregion—more than two-thirds (67%) of
stream length in the Ridge ecoregion has fish assemblages in either good or marginal condition.
The two coal mining regions (North and Central Appalachians, and Western Appalachians) had
the smallest proportion of stream length in the combined good/marginal classes (53% and 58%,
respectively).
Setting Expectations for Ecological Condition
How do we use reference sites (once they are identified) to help set our expectations for biology?
To help explain this process, it is useful to employ a familiar analogy. Suppose that you wanted to use
human body temperature as an indicator of human health (as is commonly done). One of the first
things you would need is information on the normal range of temperatures. In order to estimate this
range, or distribution, you might draw a subsample of the human population that is considered
'healthy.' The range of temperatures measured in this subsample is an estimate of reference condition
for this indicator. Next, we'd want to know how far away from this distribution (or how extreme) a
temperature needs to be before we'd consider it to be unhealthy. In the case of body temperature, we
might have very high confidence that we've correctly identified a healthy subpopulation, and the
range of temperatures might be fairly small. In this case, we could use something like the ends or
extreme values from the reference distribution (e.g., the lowest 1% or the highest 1% of body
temperatures measured from a large group of people), as thresholds beyond which we identify a
temperature as unhealthy.
We use a similar approach for the biological data we report for the Mid-Atlantic region—
identifying a healthy subsample of sites (i.e., reference sites), collecting indicator information on each
one, and describing a distribution of reference condition values. But we have less confidence that all
of the sites we identify as 'healthy' truly are. We can't know to what extent we've missed unknown
or unobserved stressors to ecological condition, or the degree to which small amounts of degradation
at our reference sites influence the distribution of metric and index scores.
For this reason, we use more conservative thresholds than we used in the body temperature
example. Commonly, the 25th percentile value (of the reference distribution) is used as a threshold
st
between sites in good condition, and those in fair or marginal condition. We also adopt the 1
percentile as the threshold between sites in marginal condition and those in poor condition. For these
sites, we can be 99% confident that their biotic integrity is lower than anything found in our
subsample of sites in least disturbed condition (more information on setting expectations can be
found in Appendix A).
MACROEVVERTEBRATE ASSEMBLAGES
An additional picture of stream and river condition can be derived from examining the
macroinvertebrates (aquatic insects, snails, worms and other benthic invertebrates) in streams
and rivers. These animals provide food for fish and other wildlife, and serve as a link between
the algae and higher levels of the ecological food web. Macroinvertebrates are considered to be
very good indicators of chemical stresses (e.g., acidity) as well as excess inputs of fine sediment
from local landuse.
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 20
-------
We use an approach identical to that for fish to develop an Index of Biotic Integrity for
macroinvertebrates—finding metrics or characteristics (e.g., the number of mayfly species, the
number of caddis fly species, the pollution tolerance of the species) of the assemblages that are
repeatable, responsive to human disturbance), and that contain the most information about the
health of the assemblage, and combining them into a single IBI score. And as with fish, we use
reference sites to set expectations for the individual metrics and the IBI itself (more information
in Appendix A).
MAIA Region Overall
margin of error ± 5%
44% i Bailey
margin of error ± 8%
North-Central
Appalachians
h«r V *. "
iS0*. /° V.
Pi&dmont
margin of error ± 14%
Macromvertebrate
Biotic Integrity
• Good
O Marginal
• Poor
Figure 10. Macromvertebrate IBI scores in Mid-Atlantic flowing waters, and the proportion
of the total stream length in good, marginal and poor condition. Red, yellow and green
markers on the map indicate the locations of individual sites that contribute to the estimates
of stream length in each condition. About 41% of the Mid-Atlantic stream length has
macroinvertebrate assemblages in poor condition. The Coastal Plain ecoregion has the
highest proportion of stream length in poor condition for macroinvertebrates (88%), while
the Ridge ecoregion has the highest proportion in good condition (49%).
For the Mid-Atlantic region as a whole, 26% of the stream length was in good condition
with respect to macroinvertebrate assemblages (Figure 10). More than 41% of the stream length
had poor macroinvertebrate integrity, and 33% of the stream length was in marginal condition.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 21
-------
There is a more uneven distribution of macroinvertebrate IBI scores across Mid-Atlantic
ecoregions than was the case for fish (Figure 10). Both the Coastal Plain (88%) and Western
Appalachian (46%) ecoregions have relatively large proportions of stream length in poor
condition (and only 0% and 13% in good condition, respectively). The ecoregions with the
highest biotic integrity for macroinvertebrates are the Ridge ecoregion (nearly 80% in good or
marginal condition) and the North and Central Appalachians (more than 72% in good or
marginal condition).
Ridge
margin of err or ± 11%
MAIA Region Overall
margin of error ± 6%
Valley
margin of error ± 14%
cfco % •_•• .£-/
North-Central
Appalachians
Western
Appalachians
V. .V ».° * \J '
/v*v* „: -iM
Piedmont
margin of error ± 3^%
Algal
Biotic Integrity
• Good
O Marginal
Poor
Figure 11. Algal IBI scores in Mid-Atlantic flowing waters, and the proportion of the total
stream length in good, marginal and poor condition. Red, yellow and green markers on the
map indicate the locations of individual sites that contribute to the estimates of stream
length in each condition. About 30% of the Mid-Atlantic stream length has algal
assemblages in poor condition. The Western Appalachian ecoregion has the highest
proportion of stream length in poor condition for attached algae (51%), while the North and
Central Appalachians have the highest proportion in good condition (45%).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 22
-------
ALGAL ASSEMBLAGES
Attached algae in streams grow on surfaces such as rocks, submerged wood, and on
individual grains of sand and gravel. We include them as an indicator of biotic integrity in
EMAP because they yield additional information and a different perspective on the ecological
condition of streams and rivers. Algae are known ecologically as primary producers, meaning
that they produce biomass solely through the process of photosynthesis. They are more directly
affected by excess nutrients, like phosphorus and nitrogen (needed for algal growth), than either
fish or macroinvertebrates. Like macroinvertebrates, algae have strong responses to other
chemical stresses (like acidity) and disturbances to stream substrates (i.e., sedimentation).
The same approach to building an Index of Biotic Integrity was used for attached algae as
we used for fish and macroinvertebrates. For the Mid-Atlantic region as a whole, 30% of the
stream length was in good condition with respect to algal assemblages (Figure 11). A similar
proportion of stream length had poor algal integrity (33%), and 37% of the stream length was in
marginal condition.
On an ecoregional basis, algae suggest that the Western Appalachians have the poorest
biotic integrity (51% of stream length in poor condition), followed by the Coastal Plain (35% in
poor condition) and Piedmont (37% in poor condition) ecoregions (Figure 11). The algal IBI
suggests that the mostly forested, upland ecoregions (the North and Central Appalachian, and
Ridge ecoregions) have the best biotic integrity (81% and 79% in either good or marginal
condition, respectively. These results are consistent with the types of human disturbance to
which we expect algal assemblages to respond; both upland ecoregions have relatively small
amounts of agricultural landuse, which helps to keep stream nutrient levels low, and relatively
little human uses of the land that contribute fine sediments to streams (e.g., agriculture and
mining).
COMPARISON OF FISH, MACROINVERTEBRATE,
AND ALGAL SCORES
Differences among estimates of ecological condition based on fish, macroinvertebrates and
algae are expected, because these three groups of organisms respond to different disturbances in
the environment. For the region as a whole, macroinvertebrates suggest the poorest biotic
integrity, with 41% of Mid-Atlantic stream length in poor condition according to the
macroinvertebrate Index of Biotic Integrity (Table 2). At the level of individual ecoregions, the
fish IBI tends to suggest the fewest miles of stream in good condition. The only exceptions to
this general pattern are the Coastal Plain and Western Appalachians, two highly modified
ecoregions with substantial urban (Coastal Plain) and agricultural/mining (Western
Appalachians) land use. None of the streams sampled in the Coastal Plain exhibited good
macroinvertebrate integrity, and only 8% of stream length in the Western Appalachians had good
algal integrity.
Such differences can be attributed to a number of factors. As already stated, fish and
macroinvertebrates are expected to respond differently to stresses, and the differences in the
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 23
-------
relative scores of the fish and aquatic insect scores in different ecoregions (where different
stresses are known to dominate) may be indicative of this.
Table 2
Comparison of fish, macro-invertebrate and algal IBI results for Mid- Atlantic flowing
waters, and the six ecological regions.
Region
Mid-Atlantic
Region
Coastal Plain
Piedmont
Valleys
Ridges
North/ Central
Appalachians
Western
Appalachians
% in Good Condition
TT u Macro- A1
Fish . , Algae
invertebrates
21 26 31
20 0 35
20 20 27
19 26 25
26 49 42
23 40 45
19 13 8
% in Poor Condition
„. , Macro- A1
Fish • . . ^ Algae
invertebrates
31 41 33
43 88 41
20 42 37
33 45 34
26 20 21
40 28 19
28 46 51
Even if the condition estimates for the three biotic assemblages are fairly similar (e.g., 21-
30% of stream length in good condition; 31-33% in poor condition), one might wonder whether
the three IBIs are classifying the same streams as either good or poor. And the answer to this is
"sometimes." Of the stream length classified as in good condition with respect to fish, about 70%
would also be classified as good using the macroinvertebrate IBI. Likewise, about 71% of stream
length in good condition with respect to macroinvertebrates also exhibits good algal condition.
Not surprisingly, the poorest association in IBI scores is between fish and algae; about 52% of
stream length with good fish IBI scores also have good algal IBI scores. Assemblages that utilize
habitat at different scales (like fish and algae) are expected to have more distinct responses to
stressors.
Of the roughly 220,000 km of streams in the Mid-Atlantic region, roughly 107,000 km
(48%) has one or more of the biotic assemblages in good condition, but only about 7,850 km
(3.5%) would be classified as good by all three IBIs. There are 129,000 km of Mid-Atlantic
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 24
-------
streams (58% of the total) that are classified as poor using one or more of the assemblages; fewer
than 4,350 km (2.0%) would be scored as poor using data from all three assemblages. The vast
majority of stream length in the region exists in a middle ground, where one assemblage may be
in good condition and the others in marginal or poor condition. In this middle ground, streams
and rivers are experiencing different sorts of stress; those stressors that are present are affecting
only one or two of the assemblages, and the different responses of the biotic assemblages
produce differences in how we might view the ecological condition of the sites. Only by looking
further into the relative extent of these stressors, and into how they differentially affect the biotic
assemblages we use to assess ecological condition, can we begin to understand the different
stories told by fish, macroinvertebrates and algae, and assess the overall condition of flowing
waters in the Mid-Atlantic region.
STRESSORS IN MAIA FLOWING WATERS
In the previous section, the ecological condition of the flowing waters in the Mid-Atlantic
region was described based on direct measurements of stream and river biota. Here we present
our findings on the stressors to the streams/rivers of the Mid-Atlantic. These are based on direct
measures of physical, chemical or biological characteristics of streams and their watersheds.
They are stream and river attributes that can be directly or indirectly altered as a result of human
activity or intervention in the stream system, and that have been known to have harmful effects
on stream and river biota. We present this information in the belief that comparisons of
stressors, like the ones we present here, will be useful to regional managers in determining where
best to focus their limited resources for stream and river protection and restoration. Additional
technical information on the potential stressors and their measurement can be found in the
references listed in Appendix A.
We have two primary goals in assessing stressors in the flowing waters of the Mid-Atlantic.
We hope to:
1. Estimate the relative extent of each stressor (i.e., the percentages of stream length having
"poor" stressor condition), demonstrating which stressors are most common. Relative
extent is one measure of each stressor's relative importance.
2. Calculate each stressor's relative risk to the biological assemblages we've used to assess
ecological condition. Relative risk measures the association seen in our data between
poor biological condition and poor stressor condition. It answers the question, "How
much more likely is a given biological measure (e.g., a fish IBI) to indicate poor
condition if a given stressor (e.g., riparian habitat) is also in poor condition?" We use
relative risk as an indicator of the severity of stressor effects on biological assemblages.
For each stressor, a brief description of the nature of the measurements is provided,
followed by the results. Wherever possible, we have used a similar strategy for assessing
stressors as we have for biological measures—the distribution of values in a set of relatively
undisturbed sites (reference sites) is used as a measure of what constitutes acceptable values for
these stressors. This distribution of reference site scores is used to determine whether, and to
what extent, the scores of other sites fall outside this distribution (more information on the
reference site approach is given in Appendix A).
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 25
-------
At the end of this section, we present the relative extent and relative risks of the stressors for
the Mid-Atlantic as a whole, so that the reader can develop some appreciation of both the extent
and the severity of individual stressors. As with the indicators of ecological condition, we also
present the relative extent of stressors for each of the six ecological regions. Unfortunately (due
to the constraints of small sample sizes) we cannot calculate relative risk on the scale of
individual ecoregions.
Landtover
I I Open water
I I Low Intensity Residential
I I High Intensity Residential
• Commercial/lndustrial/Transportation
I I Bare Rock/Sand/Clay
I I Quarry/Strip Wine/Gravel Pit
C! Transitional
• Deciduious Forest
• Coniferous-Forest
• Mixed Forest
I I Pasture/Hay
• Row Crop
HH Urban/Recreational Grass
• Woody Wetland
I I Emergent'Herbaceous Wetland
Figure 12. Land use and land cover in the Mid-Atlantic region, as determined from satellite
imagery.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 26
-------
The heterogeneous nature of the land use and land cover in the Mid-Atlantic region is
evident from satellite imagery (Figure 12). Agricultural areas, urban and suburban clusters,
forests, mining sites, and other features are interwoven on the landscape, with many of these
features indicating human activity. These human activities have the potential to alter stream and
river quality and affect aquatic biota. The characteristics or stressors in Mid-Atlantic streams and
their watersheds included in this report are:
(1) Stream/river acidification (from acid rain and mining),
(2) Other mining impacts,
(3) Nutrient runoff,
(4) In-stream habitat alteration (e.g., sedimentation, wood removal),
(5) Riparian habitat alteration,
(6) Non-native fish introductions.
ACIDIFICATION
Streams and rivers can become acidic through the effects of acid deposition (acid rain) or
due to mine drainage (particularly from coal mining). The Mid-Atlantic region is unusual
because it receives some of the highest rates of acid rain in the U.S., has geology that makes
large areas within the region susceptible to acidification, and has a high incidence of coal
mining.
Acid rain forms when the emissions from smokestacks and automobiles (particularly sulfur
dioxide and nitrogen oxides) combine with moisture in the air, forming dilute solutions of
sulfuric and nitric acid. Acid deposition can also occur in dry forms, like the particles that make
up soot. When wet and dry deposition fall on sensitive watersheds, like those in the upland
portions of the Mid-Atlantic, they can have deleterious effects on soils, vegetation and streams
and rivers. In assessing acid rain's effects on flowing waters, we rely on a measure of the water's
ability to buffer inputs of acids, called acid neutralizing capacity or ANC. When ANC values fall
below zero, the water is considered acidic, and can be either directly or indirectly (e.g., by
mobilizing toxic metals like aluminum) toxic to biota.
Acid mine drainage forms when water moves through mines and mine tailings, combining
with sulfur-bearing minerals to form strong solutions of sulfuric acid, and mobilizing many toxic
metals. As in the case of acid rain, we can assess the acidity of waters in mining areas by using
their ANC values. Mine drainage also produces extremely high concentrations of sulfate—much
higher than those found in acid rain. While sulfate is not directly toxic to biota, we use it as an
indicator of mining's influence on streams and rivers. When ANC and sulfate are low, we can
attribute acidity to acid rain. When ANC is low and sulfate is high, we can attribute acidity to
acid mine drainage.
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 27
-------
3% 2%
"•—•"T
MAIA Region Overall
margin of error ± 5%
Acid Deposition
• None
O Episodic
• Chronic
Ridge
margin of error ± 3%
Valley
margin of error ± 8%
Nofth-Cenlfal
Appalachians
margin of error ± 7%
Western
Appalachians
margin of error ±
Piedmoni
' margin of error *
Coastal
Plain
margin of error ± 24%
Figure 13. Extent of acid deposition effects on flowing waters of the Mid-Atlantic, and the
proportion of the total stream length in unacidified, episodically acidified and chronically
acidified categories. Roughly 5% of the region's stream length exhibits effects of acid
deposition. Nearly all of the stream length affected by acid deposition in the Mid-Atlantic is
in the North and Central Appalachian (14%) and Ridge (8%) ecoregions.
Streams and rivers may be acidic throughout the year (chronically acidic) or only for short
periods (episodically acidic), such as when flows are high during storms or snowmelt. Both
forms of acidity have deleterious effects on biota, including all of the biological assemblages we
are using in this assessment. Data from streams sampled during spring and summer, like those in
this Mid-Atlantic assessment, can be used to assess directly the incidence of chronic
acidification. Across the region as a whole, just over 2% of the total stream length is chronically
acidic (ANCXO) due to acid rain. In order to estimate how this number would change if we
considered both chronic and episodic acidity, we change the ANC threshold to 50 jieq/L—the
National Acid Precipitation Assessment Program concluded in 1990 that streams with ANC
values lower than 50 jieq/L are susceptible to episodic acidification, and may experience fish
kills and changes to their macroinvertebrate communities during short-term pulses of acid rain
runoff. When both chronic and episodic acidity are considered, we conclude that about 5% of
the total stream length in the region is affected by acid rain (Figure 13).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 28
-------
1%1%
"•—•"T
MAIA Region Overall
margin of error ± 5%
I
* * if ^"y.-** i*c>
°rffc>^V*ft f ••/
Acid Mine Drainage
• None
O Moderate
• Severe
4% 1%
3% 1%
Ridge
margin of error ± 3%
Valley
margin of error ± 8%
North-Centra!
Appalachians
margin of error ± 7%
Western
Appalachians
margin of error ± 12%
Piedmont
margin of error ±
Coastal
Plain
marginof error ± 24%
Figure 14. Extent of acid mine drainage in flowing waters of the Mid-Atlantic, and the
proportion of the total stream length in unaffected, moderately affected, and severely
affected categories. Acid mine drainage is not as common in the Mid-Atlantic as acid
deposition effects, with about 2% of stream miles affected. All of the stream length affected
by acid mine drainage in the Mid-Atlantic region is in the North and Central Appalachian
(5%) and Western Appalachian (4%) ecoregions.
For problems such as acid rain and acid mine drainage, an ecoregion perspective is
particularly appropriate. Ecoregion designations integrate similar geology, soils, watershed
topography, climate and vegetation characteristics that help explain stream responses to certain
types of stressors or pollution. Some ecoregions have streams that are much more susceptible to
acid rain because they lack the limestone and other well-buffered bedrocks that help protect
streams from acidic inputs. Due to these ecoregional differences, nearly all of the streams in the
Mid-Atlantic affected by acid rain are in two ecoregions (Figure 13). About 8% of the stream
length in the North and Central Appalachians is chronically acidic, and an additional 6% is
affected by episodic acidification. Fewer streams are chronically acidic in the Ridge ecoregion
(less than 1% of total stream length), but combined episodic and chronic acidification affect 7%
of the total length. None of the other ecoregions has more than 0.5% of stream length affected by
acid rain.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 29
-------
The extent of acid mine drainage is substantially less than acid deposition—only 2% of the
stream length in the Mid-Atlantic is acidic due to mine drainage (Figure 14), with more than half
of these streams exhibiting chronic acidity. All of the acid mine drainage streams are located in
the Appalachian ecoregions where coal mining is common. In the North and Central
Appalachians, just under 5% of stream length is affected by acid mine drainage; 4% of the
stream length is severely and chronically acidic (Figure 14). The Western Appalachian ecoregion
has acid mine effects in roughly 4% of its stream length.
MAIA Region Overall
margin of error ± 5%
Mine Drainage
• None
O Moderate
• Severe
7%
Ridge
margin of error ± 8%
Valley
margin of error:
North-Centra!
Appalachians
margin of error ± 7%
43% 1 Western
Appalachians
margin of error ± 12%
Piedmont
margin of error ± 13%
Coastal
Plain
margin of error ±24%
Figure 15. Extent of all mine drainage effects on flowing waters of the Mid-Atlantic, and the
proportion of the total stream length in good, marginal and poor condition with respect to
mining indicators. Roughly 17% of the region's stream length exhibits effects of mine
drainage. Nearly all of the stream length affected by mine drainage in the Mid-Atlantic is in
the North and Central Appalachian (27%) and Western Appalachian (57%) ecoregions.
In total, there are some 9,600 kilometers of Mid-Atlantic flowing waters that are acidic due
to acid rain or susceptible to acid rain, and about 4,100 kilometers that are acidic due to mine
drainage.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 30
-------
OTHER MINING EFFECTS
Streams that are acidic due to mine
drainage are less common in the Mid-
Atlantic than streams acidified by acid rain,
but mine drainage effects extend far beyond
acidification. Downstream effects of mines
include export of fine sediments and toxic
metal contamination (metals reside
primarily in stream bottom sediments in
non-acidic streams); these less well-known
stresses can have pronounced effects on
bottom-living organisms. Although only
about 2% of stream miles in the Mid-Atlantic are acidic because of mine drainage, an additional
15% of the stream length is non-acidic, but degraded by mine drainage (Figure 15). About 10%
of Mid-Atlantic stream miles would be considered severely affected by mine drainage (either
acidic, or with extremely elevated concentrations of sulfate indicating a dominant source of
water from mines).
Only small amounts of mine drainage effects are exhibited outside of the two coal-mining
ecoregions (Figure 15). In the Piedmont and Ridge ecoregions, roughly 1-2% of stream length is
affected by non-acidic mine drainage, due to having mines in the headwaters (the headwaters of
several rivers in the Piedmont and Ridge ecoregions are in the coal-bearing regions to the East).
In the Western Appalachians, where coal deposits are common, the majority of streams have at
least moderate indicators of mine drainage effects (57% of total length); 28% of the stream
length in this region would be considered severely affected. In the North and Central
Appalachians, 27% of the total stream length has some signs of mining effects, with 20% of
stream length having indicators of severe mine drainage affects.
NUTRIENT ENRICHMENT
The introduction of excessive nutrients (e.g., phosphorus and nitrogen) can affect streams
directly, for example by increasing algal growth, or indirectly, by altering the quality and
quantity of food for higher trophic levels like macroinvertebrates and fish. In extreme cases,
nutrients can lead to levels of algal growth that deplete the oxygen in the water, choke out other
forms of biota, and significantly alter the assemblages present. Common sources of nutrients
include municipal sewage, runoff from septic fields, and agricultural fertilizers. Atmospheric
deposition is an additional source of nitrogen (but a minor source of phosphorus), and may be
important in areas that are otherwise unaffected by urban and agricultural land uses.
The growth of algae in fresh waters (lakes and streams) in the U.S. are considered to be
primarily limited by the amounts of phosphorus present, and elevated phosphorus levels are
therefore of special concern. In the Mid-Atlantic as a whole, phosphorus concentrations would
be considered severely elevated in about 14% of stream length (Figure 16); more than 44% of
stream length in the region has phosphorus levels we would classify as good.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 31
-------
Because of its direct link to agricultural land use, phosphorus is most commonly elevated in
the ecoregions with higher percentages of agriculture—the Piedmont (29% of stream length with
severely elevated phosphorus), Western Appalachian (16%) and Valley ecoregions (12%). The
primarily forested areas of the Mid-Atlantic, the North and Central Appalachian and Ridge
ecoregions, have a majority of their stream length (66% and 60%, respectively) in good
condition with respect to phosphorus.
"•—"I"
Total Phosphorus
Good
O Marginal
• Poor
Ridge
margin of error ± i
Valley
margin of error •
4%
r30% ^ \ North-Central
66% J Appalachians
margin of error ± 7%
Western
° / Appalachians
margin of error* 12%
56% 1 Piedmont
\y ^X margin of error ±
Coastal
Plain
margin of error ±24%
Figure 16. Extent of excess phosphorus concentrations in flowing waters of the Mid-Atlantic,
and the proportion of the total stream length in good, marginal and poor condition with
respect to this nutrient. Roughly 14% of the region's stream length exhibits excessive
phosphorus concentrations. The Piedmont ecoregion has the highest proportion of streams
(29%) with poor phosphorus concentrations.
Nitrogen is another nutrient that can stimulate plant growth, especially in the presence of
high phosphorus concentrations. Like phosphorus, nitrogen is commonly found in agricultural
fertilizers, but may also originate in acid rain (nitrogen deposition), animal manure, and sewage
discharges. Overall, 17% of Mid-Atlantic stream length would be considered to be in poor
condition with respect to nitrogen (Figure 17); more than 40% has good nitrogen levels.
Although both phosphorus and nitrogen result from fertilizer runoff, and other agricultural
practices, additional sources of nitrogen lead to a different ecoregion distribution for this nutrient
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 32
-------
(Figure 17). Nitrogen (either as nitrate or ammonium) can be a major component of atmospheric
deposition, and results both from the combustion of fossil fuels (especially in vehicles) and the
release of gaseous forms of nitrogen from confined animal feedlots. The Valley (39%) and
Coastal Plain (25%) ecoregions exhibit the highest proportions of stream length with severely
elevated nitrogen, while the forested ecoregions again have the highest proportions of streams
with low nitrogen concentrations (Ridge ecoregion 63%, North and Central Appalachians 48%).
MAIA Region Overal
margin of error ± 5%
Total Nitrogen
• Good
O Marginal
• Poor
7%
Ridge
margin of error ± 8%
Valley
margin of error ± 8%
Nofth-Centra!
Appalachians
margin of error ± 7%
Western
Appalachians
margin of error ± 12%
Piedmont
margin of error ± 13%
Coastal
Plain
margin of error ± 24%
Figure 17. Extent of excess nitrogen concentrations in flowing waters of the Mid-Atlantic,
and the proportion of the total stream length in good, marginal and poor condition with
respect to this nutrient. Roughly 17% of the region's stream length exhibits excessive
nitrogen. The Valley ecoregion has the highest proportion of streams (39%) with poor
nitrogen concentrations.
IN-STREAM HABITAT
High quality habitat is an important and often overlooked ingredient for good stream
condition. In the course of EMAP sampling, data were collected on many aspects of both
riparian (near-stream) and in-stream habitat known to be important to biota. These quantitative
measures of habit can be used to diagnose the possible causes of habitat degradation. We focus
in this assessment on two characteristics of in-stream habitat (sedimentation and large woody
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 33
-------
material) that play important roles in establishing high quality habitat structure for fish,
macroinvertebrates and algae.
MAIA Region Overall
margin of error ± 6%
s
Excess Sediments
• Good
O Marginal
• Poor
41% i Ridga
margin of error ±
Valley
margin of error ± 14%
North-Central
Appalachians
margin of error * 10%
Western
Appalachians
margin of error ± 13%
Pi&clmom
margin of error ± 13%
Coastal
Plain
margin of error ± 25%
Figure 18. Extent of excess sedimentation in flowing waters of the Mid-Atlantic, and the
proportion of the total stream length in good, marginal and poor condition with respect to
fine sediments. Roughly 28% of the region's stream length exhibits amounts of fine sediment
far in excess of expectations. The Coastal Plain ecoregion has the highest proportion of
streams (54%) with excess fine sediments.
In order to assess stream sedimentation, we compared
measurements of the amount of fine sediments on the bottom
of each stream (sands and fines) with expectations based on
each stream's ability to transport fine sediments downstream
(a function of the slope, depth and complexity of the stream).
Fine sediments in excess of expectations suggest that the
supply of sediments from the watershed to the stream is
greater than what the stream can naturally process. For the
purposes of this assessment, we calculated the ratio of observed to expected sediment sizes for
all streams, including reference sites, and used the distribution of ratios in the reference sites to
define the ratio's natural variability. This is the same approach used for biological measures and
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 34
-------
the other stressors in this assessment—using a set of reference streams to define expectations for
the least disturbed sites in each ecoregion (see Appendix A).
About 28% of the total stream length in the Mid-Atlantic has fine sediments far in excess of
expectations (Figure 18), but more than half (53%) were within the expected range and would be
considered to be in good condition. The Coastal Plain (54% in poor condition), Western
Appalachian (38%) and Valley (36%) ecoregions had the highest proportions of stream length
with excessive sediments (Figure 18). Somewhat surprisingly, the Piedmont ecoregion has the
highest proportion of stream length (76%) with no excess sediment problems. Note that this does
not mean that the Piedmont region had the lowest levels of fine sediment, only that the amount of
fine sediments in most of these streams are within expectations.
MAI A Region Overall
margin of error ± 6%
Appalachians
margin of error ± 10%
ft o •• ^ J • •
J * 1 • 7 . *
V* • ** *
Piedmont
margin of error ± 13%
• Good
O Marginal
• Poor
Figure 19. Extent of large wood in flowing waters of the Mid-Atlantic, and the proportion of
the total stream length in good, marginal and poor condition with respect to in-stream wood.
Roughly 26% of the region's stream length is completely devoid of large wood.
Another aspect of in-stream habitat that creates high quality habitat space for biota is the
amount of large woody material. Downed and dead trees, falling into streams from nearby
riparian areas, are widely recognized as crucial components of the complex habitats that typify
streams with high biodiversity. The amounts of wood found in Mid-Atlantic streams are quite
low compared to many other forested areas of the U.S., and may have historically been much
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 35
-------
higher. In assessing large wood, we compare present values only to those of the least disturbed
sites in the region, and not to historical estimates. If historical amounts of wood were higher as is
suspected, then an assessment using historical reference condition might well paint a different
picture.
For the Mid-Atlantic as a whole, 26% of stream length was completely devoid of large
wood (our definition of poor condition; see Appendix A), while 47% had amounts of wood
similar to reference sites (Figure 19). The Coastal Plain ecoregion presents the best picture, with
67% of stream length in good condition, and only 14% in poor condition for wood (Figure 19).
The Western Appalachian (41% of stream length in poor condition) and Valley (30%)
ecoregions had the highest proportions of stream length with no large wood.
RIPARIAN HABITAT
Riparian (or streamside) vegetation provides shade to flowing waters (particularly small
streams), maintaining cool water temperatures required by many fish species for reproduction,
growth and survival. Riparian vegetation that washes or falls into the stream can be a source of
food for stream organisms, especially macroinvertebrates. It also strengthens and stabilizes
stream banks and helps to prevent silt and associated contaminants from entering the stream. In-
stream large wood derived from riparian trees creates complex habitat and pools for stream fish
and aquatic insects. Human beings alter riparian habitat in a variety of ways: clearing vegetation
from the banks and riparian areas, logging or farming up to the stream edge, dumping litter or
other wastes in riparian areas, building roads along and across streams, adding stabilizing
structures (e.g., rip-rap) along banks, and building dams or other diversion structures in or near
the stream channel.
We incorporated aspects of riparian vegetation
cover, structural complexity, and the intensity
of human disturbances into an index of
Riparian Habitat Quality for use in this
assessment. The index ranges from zero to
one, with a value of one resulting from the
combination of: (1) a multi-storied corridor of
woody vegetation; (2) canopies that are closed
(or nearly closed; and (3) riparian areas free of
visible human disturbance (trash, roads fences,
etc.). We calculated this index for all sites, and
compared each site's score to the distribution
found in reference sites.
Riparian habitat results for the Mid-Atlantic as a whole indicate that 23% of the total stream
length had riparian areas in poor condition, while 57% had riparian habitat similar to that of
reference sites (Figure 20). The Coastal Plain (26% of stream length in poor condition) and
Western Appalachian (26%) ecoregions have the poorest riparian habitat (Figure 20). As was the
case with excess sediments, the Piedmont ecoregion has somewhat surprisingly large proportion
of stream length in good condition (77%). It may not be a coincidence that this region scored
well for both in-stream and riparian habitat, as the two are closely linked. Good riparian habitat
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 36
-------
provides protection from excess sediment that might otherwise enter the stream, as well as
supplying large woody material to streams (Figure 21). Upland areas of the Mid-Atlantic, the
North and Central Appalachian and Ridge ecoregions, also have large proportions of stream
length with good riparian condition (56% and 70%, respectively).
MAIA Region Overall
manjiboferror±
Riparian Condition
• Good
O Marginal
• Poor
Ridge
margin of error ± 10%
Vall&y
margin of erf or ± 14%
North-Central
Appalachians
margin of error ± 10%
Western
Appalachians
margin of error ± 13%
Piedmont
margin of error ± 13%
Coastal
Plain
margin of error ± 25%
Figure 20. Extent of problems with riparian condition along flowing waters of the Mid-
Atlantic, and the proportion of the total stream length in good, marginal and poor condition
with respect to riparian areas. Roughly 23% of the region's stream length exhibits poor
riparian condition. The Valley ecoregion has the highest proportion of stream length (37%)
with poor riparian condition.
NON-NATIVE FISH
To some people a thriving rainbow trout stream indicates a successful fisheries management
program. To others it suggests the introduction of a non-native, and potentially invasive,
species—and a potential loss of biotic integrity and native biodiversity.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 37
-------
0.2 0.4 0.6 0.8
Index of Riparian Habitat Quality
1.0
Figure 21. Relationship between Large Wood (an areal estimate of wood in stream) and
Riparian Condition for 592 streams in the Mid-Atlantic. High riparian habitat quality can
confer many benefits to streams and rivers, including the supply of wood to maintain
complex in-stream habitat for biota.
Some states specifically recognize trout-stocked fisheries as a "designated use" for certain
streams, yet many consider fish stocking of non-native species to be a potential stressor in the
stream. Non-native fish do not necessarily imply poor stream condition, but non-native species
have been known to replace native fish by direct predation or by out-competing them for
available habitat, food, or both. In the Mid-Atlantic as a whole, 47% of the stream length has at
least some non-native individuals (Figure 22). We don't attempt to identify classes of stream
condition for non-native species (e.g., good, marginal or poor condition based on non-native fish
species), because of the difficulty of setting expectations. The procedure we've used for all
previous indicators (biology and stressors) involves deciding what an appropriate group of
reference sites might be for that indicator, but this creates difficulties for a non-native species
indicator. Many of the reference sites (nearly 65%) that we might use for a chemical or physical
habitat indicator have at least some individuals of introduced species present. If we were using
historical condition as a reference, then it might be reasonable to expect all streams to be free of
non-native species, and any introduced species would be enough to classify a site as poor. But
the difference between historical expectations (no non-natives) and current conditions (where
65% of reference sites have non-natives) is so great as to make setting expectations nearly
impossible, especially given the differences in opinion about whether the presence of non-natives
really represents a stress at all.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 38
-------
Piedmont
margin of error ± 13%
Non-Native Fish
• None
O0-10%
Figure 22. Percentage of Mid-Atlantic stream length with non-native fish species present.
Approximately 47% of total stream length had non-native individuals present, while 46%
did not. Roughly 7% of stream length is fishless. The Piedmont ecoregion has the highest
proportion of stream length with introduced fish species (76%).
One convenient way to display information when thresholds between good, marginal and
poor condition cannot be identified, is with a graph known as a cumulative frequency
distribution or CDF. Figure 23 presents a CDF of the percentages of stream length that have
different proportions of non-native individuals. At any point on the horizontal axis, one can read
the proportion of stream length (or, more correctly in this case, the proportion of stream
kilometers that have at least some fish) that meet or exceed that level. For example, we can
estimate the proportion of stream length with 10% (or more) non-native individuals by reading
the value on the vertical axis that corresponds to the 10% value on the horizontal axis. Similarly,
the proportion of stream length dominated by non-natives (e.g., where more than half of the
individuals are non-native species) would be about 3% (i.e., the difference between 100% and
97%, read from the graph). We include these values not as suggestions for identifying classes of
impairment, but to demonstrate that the reader can form his or her own opinions of what
constitutes a "non-native fish stressor" and estimate how much of the stream resource fits these
criteria.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 39
-------
O)
C
CD
-"•o
l~
CO O
CD _O>
ffi o
M— ^-^
o jz
sJD tf)
100
90
80
70
E
O
~r\j
0 10 20 30 40 50 60 70 80 90 100
Percent of Non-Native Individuals
Figure 23. Cumulative frequency distribution for the percentage of non-native fish in
flowing waters of the Mid-Atlantic. Approximately 50% of the stream miles where fish are
found had no non-natives present. 18% had 10% (or more) non-natives, while about 3% of
stream miles were dominated by non-natives (more than 50% of individuals).
Individual ecoregions exhibit large difference in the presence and absence of non-native fish
species (Figure 22). The Piedmont (76% of stream length), Valley (69%) and Coastal Plain
(68%) ecoregions have the highest proportions of stream length with non-native fish present. The
Western Appalachian and North and Central Appalachian ecoregions have the highest
proportions of streams where only native species were found (65% and 53% of stream length,
respectively).
CONTAMINANTS IN FISH TISSUE
EPA has established criteria to protect both human beings and fish-eating wildlife from
chemical contaminants that can be concentrated in fish tissue. For the MAIA study, fish tissue
samples were collected and analyzed (whenever a sufficient number of fish were caught) for
selected organic and metal contaminants. We report here on results for mercury and a combined
index of organic contaminants. In general, these results are intended to indicate the exposure to
wildlife from these chemicals, rather than the risks of human consumption. We analyzed whole
fish, rather than fillets, and so our analyses included portions offish not commonly consumed by
human beings.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 40
-------
In order to place stream sites in condition classes, we used a wildlife criterion, based on
American river otter (Lontra canadensis), of 0.1 micrograms per gram - a site where any fish
species exceeded this concentration was considered to be in poor condition with respect to
mercury (additional information on the mercury criterion can be found in Appendix A. For the
MAIA region as a whole, 19% of the stream and river length had fish exceeding this criterion
(Figure 24). An important caveat in interpreting this statistic is that 36% of the MAIA stream
length either had no fish, or did not have sufficient fish to allow contaminant measurements.
While it seems likely that some proportion of this 36% of stream length would also have had fish
with elevated mercury, the exact proportion is not known. The highest proportions of stream
length with elevated mercury in fish were found in the Piedmont (31%) and Coastal Plain (29%)
ecoregions. The ecoregion with the fewest streams with elevated mercury was the Valley
ecoregion (10% of stream length).
MAIA Region Overall
margin of error ± 6%
'• • a - ••"" °'
*—T- «
! /-^ K
i -* !•'•'•
->Q ' » »° /
Joi * • t f V F' '
°;^° T/-..
-v- •* '-y~ *
- * ° •^•:;*'.':* * ^ •>
-/I*"* * * »o •
i y °
• • V- * -^
Mercury in Fish
• Good
• Poor
O Insufficient data
10%
Ridge
margin of error ± 13%
Valley
margin ot en of ± 13%
North-Central
Appalachians
margin of error ±10%
Western
Appalachians
margin of error ± 12%
Piedmont
margin of emt~± 13%
Coastal
Plain
margin of error ± 12%
Figure 24. Percentage of Mid-Atlantic stream length with mercury concentrations in fish
tissue that exceeded the criterion for American river otter. Approximately 19% of total
stream length had elevated mercury concentrations present, while 46% did not. About 36%
of the stream length either had no fish, or insufficient fish to allow contaminant analysis. The
Piedmont and Coastal Plain ecoregions exhibited the highest proportions of stream length
with fish mercury concentrations exceeding the 0.1 microgram per gram criterion (31% and
29%, respectively).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 41
-------
Fish tissue samples were also analyzed for several organic contaminants, including
Chlordane, DDT and its metabolites, Dieldrin and Polychlorinated Biphenyls (PCBs). Most of
these contaminants (with the exception of PCBs) are primarily from agricultural chemicals, and
might be expected to be higher in ecoregions dominated by agriculture. We placed all streams
where any fish species exceeded the American river otter criterion for any of these organic
contaminants in the poor condition category (see Appendix A for additional information on the
wildlife criteria used for these contaminants). Only 4% of the total stream and river length in
MAIA contained fish that exceeded any of the organic contaminant criteria (Figure 25). As was
the case for mercury, these results need to placed in context—about one-third (34%) of the
MAIA stream length either contained no fish, or did not have sufficient fish to allow contaminant
analysis, so the 4% estimate should probably be considered a lower bound on the true value.
Unlike mercury, where the Valley ecoregion had a low proportion of stream length with elevated
concentrations, organic contaminants are more likely to be found in the Valley (8% of stream
length) than any other ecoregion. This most likely reflects the different sources for these two
categories of contaminants—while the organic contaminants are primarily agricultural
chemicals, mercury is thought to derive mostly from atmospheric precipitation.
MAIA Region Overall
margin of error ± 6%
Organic Contaminants
in Fish
Good
• Poor
O Insufficient data
6%
Ridge
margin of error ± 14%
Valley
margin of eror± 13%
North Central
Appalachians
margin of envr± 11%
Wostorn
Appalachians
margin ofeimi'± 12%
Piedmont
margin of error ± 12%
Coastal
Plain
manpn of ero/"± 22%
Figure 25. Percentage of Mid-Atlantic stream length with organic contaminant
concentrations in fish tissue that exceeded the criterion for American river otter.
Approximately 4% of total stream length had elevated concentrations of either Chlordane,
DDT, Dieldrin or PCBs in fish. The Valley ecoregion exhibited the highest proportions of
stream length with elevated organic contaminant concentrations (8%).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 42
-------
SUMMARY RANKING OF POTENTIAL STRESSORS
An important prerequisite to making wise policy and management decisions is
understanding the relative magnitude or importance of current stressors. There are multiple ways
that we might choose to define "relative importance" with stressors. One aspect to consider is
how common each stressor is—i.e., what is the extent, in kilometers of stream, of each stressor
and how does it compare to the other stressors? We might also want to consider the severity of
each stressor—i.e., how much effect does each stressor have on biotic integrity, and is its effect
greater or smaller than the effect of the other stressors? Ideally, we'd like to combine these two
factors (extent and severity) into a single measure of relative importance. Currently we have no
good method for producing this combined measure. For this reason we present separate rankings
of the relative extent and the relative severity of stressors to flowing waters in the Mid-Atlantic.
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
0% 10% 20% 30% 40%
% of Stream Length
50%
Figure 26. Relative extent of major stressors on stream condition in the Mid-Atlantic. Each
bar represents the proportion of stream length in poor condition for that stressor, with 90%
confidence intervals around each estimate. If introduced fish species are considered a
stressor, then they are the most common stressor in the Mid-Atlantic. All of the physical
habitat indicators also rank high in relative importance based on extent.
RELATIVE EXTENT
In Figure 26, stressors are ranked according to the proportion of stream/river length
impaired (or in poor quality) with regard to each stressor indicator. The potential stressor that
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 43
-------
occurs in the highest proportion of flowing waters is non-native fish (47% of the stream length in
the Mid-Atlantic had at least one non-native fish present). As discussed earlier in this report,
many would not consider non-native fish (often game fish) to be a stressor; we list it here to
highlight the broad extent of non-native fish in the region—indicating a potentially serious
alteration of biological integrity—and leave it up to the reader to decide whether it should be
considered a stressor in the same way as other stressors. The three next-most common stressors
are elements of stream habitat: excess sediments (28% of stream length), absence of large woody
debris (26%) and low riparian habitat quality (23% of stream miles). In terms of rank, the habitat
stressors are followed by several chemical stressors (mercury, nutrients, acidity)—these are
found less extensively in the Mid-Atlantic than habitat stressors. Elevated mercury in fish tissue
(19% of stream length), excess nitrogen (18% of stream miles) and phosphorus (14%) are still
very common, as are the effects of mine drainage (10% of stream length). The percentage of
stream length affected by acid rain (5%), organic contaminants offish tissue (4%), and acid mine
drainage (1%) appear minor when compared to the other stressors, at least at the scale of the
Mid-Atlantic as a whole. They are clearly of greater relative importance in selected ecoregions
(Figures 13 and 14).
RELATIVE RISK
In order to address the question of severity of stressor effects, we borrow the concept of
"relative risk" from medical epidemiology, because of the familiarity of the language it uses. We
have all heard, for example, 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 four times higher for a person with total cholesterol of 300 mg
than for a person with 150 mg. total cholesterol.
In Figure 27 we present relative risk values for the biological and stressor data on streams in
the Mid-Atlantic. Because different biological assemblages are expected to be affected by
different stressors, relative risk is calculated separately for the fish IB I, the macroinvertebrate IBI
and the algal IBI. In our case, relative risk is defined as the proportional increase in the
likelihood of encountering a poor IBI score when a stressor's condition in the same stream is also
classified as poor (see Appendix B for details of relative risk calculation). Not all relative risks
are statistically significant, and so we focus this assessment on those that are.
In an assessment of relative risk based on cross-sectional survey data (as opposed to data
from a controlled experiment) it is impossible to separate completely the effects of individual
stressors that often occur together. For example, streams with high nitrogen concentrations often
exhibit high phosphorus as well; non-acidic streams with mines in their catchments often have
sediments far in excess of expectations. The analysis presented in Figure 27 treats the stressors as
if they occur in isolation, even though we know they do not. We do not currently have an
analytical technique to separate the effects of correlated stressors, other than to point out in the
discussion where co-occurrence of stressors should be considered in the interpretation of the
assessment.
One of the most important conclusions from the analysis in Figure 27 is that different
biological assemblages appear to be affected by different stressors. We certainly expect this to be
the case (it is the primary justification for including multiple assemblages in monitoring
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 44
-------
programs, and in assessments like the current one), but the results in Figure 27 are strong
confirmation of this. The presence of non-native fish species is associated with poor fish
assemblage integrity, but does not appear to affect either macroinvertebrates or algae. Excess
sediments present a significantly elevated risk to both macroinvertebrate and algal assemblages,
but not to fish. Acidic deposition and acid mine drainage put fish and macroinvertebrate
assemblages at risk, but do not appear to increase the likelihood of finding algal assemblages in
poor condition.
Fish
Macroinvertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acid Deposition
Orgainc Contaminants
Acid Mine Drainage
0.0 0.5 1.0 1.5 0.0 0.5 1.0 1.5
Relative Risk
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Figure 27. Relative risk values for associations between biotic integrity (for each
assemblage) and stressor condition (for each assessed stressor). Length of bars is the
increase in likelihood of encountering a poor ecological condition (based on biological
indicators) when the stressor is also ranked as poor. For example, algal assemblages are
roughly three times as likely to be in poor condition when phosphorus concentrations are
also poor. Lines (with caps) within bars indicate one-sided lower 95% confidence intervals
for estimated relative risk. A relative risk of 1.0 denotes "no stressor effect", and stressors
with confidence intervals lying entirely above 1.0 are statistically significant (one-sided
p<=0.05), as represented by yellow bars. Grey bars represent stressors for which we could
not detect a significant effect.
The significant relative risks in Figure 27 give us an idea both of how severe each stressor's
effect on biotic integrity is, and which stressors we might want to focus on when a given
assemblage is in poor ecological condition. Both algae and macroinvertebrates exhibit high
relative risks for a mix of physical and chemical habitat indicators. For example, the stressors
with significant relative risk values for algae are excess sediments and the two nutrients,
phosphorus and nitrogen. Algal assemblages are 1.5 to 3 times more likely to be in poor
condition when one (or more) of these stressors is elevated. As mentioned earlier, algae are
expected to be directly effected by elevated nutrient concentrations, because they are the only
primary producers among the biological indicators in this assessment. In fact, the relative risk of
nutrient effects on algae are the highest ones observable in our data. Sediments, which have an
obvious and deleterious scouring effect on attached algae, also appear to pose a significant risk to
algal biotic integrity.
The greatest relative risks to macroinvertebrates are excess sedimentation, mine drainage
(either acidic or non-acidic) and acidic deposition. Again, these quantitative results demonstrate
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 45
-------
what we expect qualitatively from macroinvertebrate assemblages—namely, that disturbances
that alter the micro-habitats within streams, or affect pollution intolerant taxa, have significant
effects on macroinvertebrate integrity. Most macroinvertebrate species occupy either the small
spaces between coarse streams substrates like cobbles and gravels, or cling to hard surfaces
exposed to stream currents—both micro-habitats are buried when excess fine sediments are
present in a stream. Figure 27 illustrates both the direct risk we calculate from excess sediments,
and the associated risk posed by non-acidic mine drainage, where excess sediments are likely to
occur. The direct chemical effects of acidification, whether from acidic deposition or acid mine
drainage, are also associated with elevated risks for macroinvertebrates.
In the case offish assemblages, the significant stressors are a mix of chemical, physical and
biological habitat indicators. The presence of non-native fish species, and the absence of large
woody material, are both strongly associated with poor fish biotic integrity in our dataset.
Acidity, whether from acidic deposition or acid mine drainage, is also strongly associated with
poor fish assemblages, due to the well documented loss of sensitive taxa in acidic streams.
Nitrogen and phosphorus are not expected to have direct effects on fish biotic integrity, but our
data suggest significant relative risk values for these nutrients. We cannot determine from these
data whether nitrogen and phosphorus are simply associated with other factors that have direct
effects on fish (e.g., the many cumulative effects of agricultural landuse), or whether the other
biotic alterations that occur in streams with high nutrients (increased algal growth, increased
occurrence of low oxygen concentrations) have effects that reverberate up the trophic pyramid to
affect fish.
The results in Figure 27 also illustrate that almost all of the stressors we measure have a
significant effect on at least one biotic assemblage. The only exception to this is riparian habitat
condition. Interestingly, riparian habitat is the only stressor indicator that does not result from
direct, in-stream measurements. Previous research has shown that riparian habitat is related to
many of the other stressors we measure in the streams—for example, good riparian condition is
associated with nutrient removal from agricultural runoff, control of erosion (and therefore
control of excess sediments) and the provision of dead wood to streams to support complex in-
stream habitat (see Figure 21). The lack of response in our relative risk analysis may have more
to do with the scale at which we assess riparian habitat (e.g., our measurements include only the
riparian habitat along the study reach where biota are sampled—measurements made at the scale
of the whole watershed, or along an entire stream network may capture more of the disturbance
signal) than its lack of importance to ecological condition.
COMBINING EXTENT AND RELATIVE RISK
The most comprehensive assessment of the effect of stressors on biotic integrity comes
from combining the relative extent (Figure 26) and relative risk (Figure 27) results—stressors
that pose the greatest risk to individual biotic assemblages will be those that are both common
(i.e., they rank high in terms of extent in Figure 26) and whose effects are potentially severe (i.e.,
exhibit high relative risk ratios in Figure 27). In order to evaluate these combined measures of
stressor importance, we present the relative extent and relative risk results for each assemblage in
a side-by-side comparison, below.
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 46
-------
A quick examination of the combined fish results (Figure 28) suggests that both non-native
species and the absence of large woody material in streams are highly important stressors to fish
biotic integrity—both demonstrate significant relative risks, and both are found in more than
25% of Mid-Atlantic stream length. Elevated nutrient concentrations also appear to pose
significant risk to fish assemblages, but are found less extensively (roughly 15% of stream
length). And the effects of acidic deposition and acid mine drainage are severe when found
(relative risk > 1.5), but are relatively rare in the Mid-Atlantic (less than 5% of stream length).
Relative Extent of Stressors
Relative Risk to Fish
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acid Deposition
Orgainc Contaminants
Acid Mine Drainage
0%
10% 20% 30% 40%
% of Stream Length
50%
2.0 2.5
Relative Risk
3.0
Figure 28. Comparison of relative extent (left panel) and relative risk to fish (right panel).
All stressors with relative risk values greater than 1.5 are significant (see Figure 27) for fish;
stressors with relative risk values less than one are not shown. Stressors that represent the
greatest risk to fish assemblages are characterized by high values for both extent and
relative risk (e.g., non-native fish).
Relative Extent of Stressors
Relative Risk to
Macro in vertebrates
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acid Deposition
Orgainc Contaminants
Acid Mine Drainage
0% 10% 20% 30% 40% 50%
% of Stream Length
Relative Risk
Figure 29. Comparison of relative extent (left panel) and relative risk to macroinvertebrate
biotic integrity (right panel). All stressors with relative risk values greater than 1.4 are
significant (see Figure 27) for macroinvertebrates; stressors with relative risk values less
than one are not shown. Stressors that represent the greatest risk to macroinvertebrate
assemblages are characterized by high values for both extent and relative risk (e.g., excess
sediments).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 47
-------
In the case of macroinvertebrates (Figure 29), excess sediments are quite clearly the most
important stressor—they are strongly and significantly associated with poor macroinvertebrate
integrity, and are relatively common (ca. 28% of Mid-Atlantic stream length). As was the case
with fish, acidic conditions can have a severe effect on macroinvertebrates when they occur
(either from acidic deposition or acid mine drainage), but their relative extent is low (<5%) and
are therefore of lower overall importance to regional macroinvertebrate integrity.
Elevated nutrient concentrations appear to be of the first importance (Figure 30) to algal
assemblages—they exhibit the highest calculated relative risk ratios in our data, and are
relatively common (roughly 15% of stream length). Excess sediments might be considered to be
of nearly equivalent importance—the relative risk to algal biotic integrity is lower than that of
nutrients, but they are nearly twice a common (ca. 28% of Mid-Atlantic stream length). No other
stressor exhibited significant relative risk values for algae.
Relative Extent of Stressors Relative Risk to Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acid Deposition
Orgainc Contaminants
Acid Mine Drainage
10% 20% 30% 40%
% of Stream Length
2.0 2.5
Relative Risk
Figure 30. Comparison of relative extent (left panel) and relative risk to algal biotic integrity
(right panel). All stressors with relative risk values greater than 1.6 are significant (see
Figure 27) for algae. Stressors that represent the greatest risk to algal assemblages are
characterized by high values for both extent and relative risk.
GEOGRAPHIC TARGETING
Throughout this assessment we have observed ecoregional differences in the condition of
MAIA flowing waters—both in ecological condition and in the relative importance of stressors.
It would be reasonable for land managers to ask, "Can we use these results to help guide (target)
how we spend our resources? Are there sub-regions of the Mid-Atlantic that we should make a
higher priority than others? Should we be tackling different problems in different areas?"
With the wealth of data collected by the MAHA and MAIA projects, we can begin to
provide answers to some of these questions. Within each ecoregion, the condition of the three
different biological assemblages, and the relative importance of different stressors, can be used
to guide stream protection and restoration goals. In this section, we provide very short summaries
of the condition assessments for each Mid-Atlantic ecoregion, and speculate briefly on what the
results might imply to managers. This comparative look at the results of an ecological
assessment might be termed "geographic targeting."
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 48
-------
COASTAL PLAIN
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
o
100
20 40 60 80
Percent of Stream Length
Figure 31. Summary of Coastal Plain ecoregion condition.
Perhaps the most striking result for the Coastal Plain ecoregion is the large proportion of
stream length in poor condition for macroinvertebrates. Although stream managers might be
tempted to focus on macroinvertebrates (or, more specifically, on the stressors that are known to
degrade their condition), it is important to recognize that all three biological assemblages are
more commonly found in poor condition in the Coastal Plain than in the Mid-Atlantic as a
whole—88% vs. 41% for macroinvertebrates, 43% vs. 31% for fish, and 41% vs. 33% for algae.
This region has the highest proportion (relative to other ecoregions) of stream length with
severe sedimentation, and the relative risk assessment (previous section) suggests strongly that
macroinvertebrates (as well as algae) are strongly affected by excess fine sediments. If stream
and watershed managers in the Coastal Plain were to focus on the single environmental problem
with the largest probability of improving biotic integrity, then controlling sediment inputs might
be a wise choice.
The Coastal Plain also exhibits a very large proportion of stream miles with non-native fish
species present. While non-native fish species are difficult to eradicate once they become
established, measures to limit further introductions and dispersal might help prevent further
degradation of the biotic integrity offish assemblages in this ecoregion.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 49
-------
PIEDMONT
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
0
80
100
20 40 60
Percent of Stream Length
Figure 32. Summary of Piedmont ecoregion condition.
Like the Coastal Plain, the Piedmont ecoregion has a larger proportion of stream length in
poor condition for macroinvertebrates than for any other biological assemblage. But unlike the
Coastal Plain, the Piedmont does not have an obvious stressor to focus on—no single stressor
known to affect macroinvertebrates (sedimentation, acidity) is particularly prevalent.
The Piedmont is instead characterized by a relatively even ranking of the most common
stressors (all of the habitat stressors and both of the nutrient stressors are found in 15% to 30% of
stream length), and the largest proportion of stream length with non-native fish (nearly 70%).
Excessive concentrations of both nitrogen and phosphorus are found in a larger proportion of
streams in this ecoregion than in the Mid-Atlantic as a whole, while the habitat stressors are
uncommon relative to the larger region. Even though nutrients rank relatively low in the Mid-
Atlantic stressor hierarchy (Figure 26), a focus on them in the Piedmont might be warranted.
Interestingly, algae are the only assemblage in the Piedmont where the proportion of streams in
poor condition is substantially higher than in the Mid-Atlantic as a whole. Our relative risk
analysis suggests that high nutrient concentrations pose a significant risk to algal biotic integrity,
and high proportions of poor stream condition for both algae and nutrients in the Piedmont
certainly suggest that a focus on nutrients would be beneficial in improving streams in the
region.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 50
-------
VALLEYS
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
o
100
20 40 60 80
Percent of Stream Length
Figure 33. Summary of Valley ecoregion condition.
In common with both of the other lowland ecoregions (the Coastal Plain and Piedmont) the
Valley ecoregion has a larger proportion of stream length in poor condition for
macroinvertebrates than for any other biological assemblage, although poor condition is found in
all three assemblages in a slightly larger proportion of streams in the Valley ecoregion than in the
Mid-Atlantic as a whole—45% vs. 41% for macroinvertebrates, 33% vs. 31% for fish, and 34 %
vs. 33% for algae.
Like the Piedmont, the Valley ecoregion is characterized by a relatively even ranking of the
most common stressors (all of the habitat Stressors, as well as nitrogen, are found in 25% to 40%
of stream length), but all have greater extents here than in the Piedmont. There has been
substantial monitoring and research work to show that intact riparian areas can help prevent
nitrogen runoff (largely from agricultural fertilizers) from reaching streams. Protecting and
restoring riparian areas in the Valley ecoregion could well lead to improvements in all of the
most common stressors in the region—controlling sediment and nitrogen inputs, and providing
additional large woody material to streams deficient in wood. Managers might well look at the
summary in Figure 33 and conclude that focusing their restoration and remediation resources on
improving riparian condition could provide the single biggest improvement in stream condition.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 51
-------
RIDGES
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
20 40 60 80
Percent of Stream Length
100
Figure 34. Summary of Ridge ecoregion condition.
The Ridge ecoregion might be considered to be in the best condition of any Mid-Atlantic
ecoregion. All three biological assemblages are found in poor condition in less than 25% of
stream length—well below the region-wide proportion for the Mid-Atlantic as a whole. It is
easier to decide what not to focus on in this ecoregion than to identify an obvious target for
restoration resources. Nutrients, for example, are a problem in 4-5% of stream length, and are
probably best managed on a site-specific basis, rather than through a region-wide effort.
As one of the few ecoregions where the proportion of stream length with poor fish
assemblages is higher than the proportion of macroinvertebrate and algal assemblages, focusing
on those stressors that represent the greatest relative risk to fish would make sense. Reducing the
extent of non-native fish, for example, may be a cost effective strategy for improving fish
assemblages.
Alternatively, regional managers might look at the relatively high biotic integrity in this
ecoregion, and conclude that efforts to conserve remaining areas of good ecological condition
should focus on this ecoregion.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 52
-------
NORTH AND CENTRAL APPALACHIANS
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
o
100
20 40 60 80
Percent of Stream Length
Figure 35. Summary of North and Central Appalachian ecoregion condition.
The North and Central Appalachians, like the Ridge ecoregion, are in relatively good
condition compared to the Mid-Atlantic as a whole (Figure 35). Only fish assemblages are found
in poor condition in a larger proportion of stream length here (40%) than in the entire region
(31%).
Relatively rare problems with sedimentation and nutrients might well be responsible for the
small proportion of algal assemblages found in poor condition. But mine drainage and acidic
deposition, both of which put fish and macroinvertebrate assemblages at risk (Figure 27), are
more extensive in the North and Central Appalachians than in the rest of the Mid-Atlantic (with
the exception of mine drainage in the Western Appalachians, below). The combined effects of
acidification and (non-acidic) mine drainage could well explain the large proportion of stream
length with poor fish IBI scores in the region. These two problems are likely to occur in different
places (acid deposition effects are found in otherwise pristine upland watersheds; non-acidic
mine drainage problems, like the transport of coal fines, are found in lower elevation watersheds
with mines in their headwaters).
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 53
-------
WESTERN APPALACHIANS
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
20 40 60 80
Percent of Stream Length
100
Figure 36. Summary of Western Appalachian ecoregion condition.
The Western Appalachian ecoregion has high proportions of stream length in poor condition
for nearly all of the common stressors (Figure 36). But the results here are not all bad news—fish
assemblages in this ecoregion are in poor condition in a smaller proportion of streams than in the
Mid-Atlantic as a whole, and the extent of non-native fish species is lower than for any other
ecoregion. Problems with biotic integrity are more common in the macroinvertebrate and algal
assemblages in the Western Appalachians, and this allows managers to focus on the stressors
likely to affect those assemblages.
Perhaps the most obvious stressor to focus on in this ecoregion is excess sedimentation.
Because it puts both macroinvertebrate and algal biotic integrity at risk (Figure 27), and is a
likely side effect of non-acidic mine drainage, sedimentation may be a reasonable target for
future stream management actions. The extent of acid mine drainage in this heavily-mined region
is quite low—perhaps as a result of control measures to control metals and acidity—but
additional measures to control the input and movement of sediments from coal mining operations
in Western Appalachian streams (e.g., improving riparian areas, also commonly degraded in the
region) could well lead to improved biotic integrity.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 54
-------
CONCLUSIONS AND FURTHER DIRECTIONS
For more than a decade, numerous organizations have decried the lack of useful information
available for producing a report card on the nation's environment. There have been two recent
efforts, the Heinz Center's State of the Nation's Ecosystems report and EPA's own Draft Report
on the Environment (see Appendix C) to produce a national report card. Both reports conclude
that, in order to produce a true assessment of the nation's environment, monitoring efforts must
be focused on collecting comparable indicators, based on consistent field protocols, and
implement a sample survey design that produces a representative set of sample sites. This MAIA
State of the Flowing Waters Assessment, and the research/monitoring program that produced its
data, provides a regional-scale template for how a national report card might one day be created.
For a report card to be effective, the information it provides must be used to make decisions
and to set future directions. An effective report card should fulfill two objectives. First, it should
describe whether there is a problem, how big the problem is, and whether the problem is
geographically localized or widely distributed. Second, it should give some clues about what
needs to be changed in order to improve ecological condition. Our MAIA assessment has
discussed both aspects.
Are there problems in the Mid-Atlantic region? We have used biological indices, based on
fish, macroinvertebrate and algal assemblages, to answer this question. The information can be
viewed from two perspectives: what is going well (i.e., how much of the resource is in good
condition) and what is not going well (i.e., how much of the resource is in poor condition).
Regardless of which assemblage is examined, the Mid-Atlantic region appears to be in trouble.
For none of the three assemblages is more than 30% of the stream resource classified in good
condition, and more than 30% of the resource is consistently assessed as in poor condition:
Percent of Stream Resource in:
Assemblage . , _,
/- j /-> 1-4.- Marginal Poor
Good Condition „ ° . „ ,. .
Condition Condition
Fish 21 42 31
Macroinvertebrates 26 33 41
Algae 30 37 33
Historically, we have focused primarily on streams in either good or poor condition, but
perhaps a third strategy is to concentrate our attention on the proportion of stream resource in the
marginal category. Following the traditional medical concept of triage, we could focus on trying
to prevent streams and rivers from slipping into the poor category, by focusing our attention on
those that are now considered marginal. As the table above suggests, a large proportion of the
resource falls into this category.
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page 55
-------
PROTECTION vs. RESTORATION
Are problems in the Mid-Atlantic region localized or widely distributed? Are there
subregions in good condition that should be targets for protection efforts? Are there subregions
in particularly poor condition that would be targets for restoration? Based on a protection
strategy, the Ridge ecoregion and the North Central Appalachian ecoregion would be targets
Figure 37). Each of these regions had over 40% of the flowing waters in good condition for at
least one of the three biological assemblages.
Ridge Ecoregion
Poor Ecological Condition
North/Central Appalachian Ecoregion
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
Stressors
20 40 60 80
Percent of Stream Length
20 40 60 80
Percent of Stream Length
100
Figure 37. Combined results for two subregions that could be targeted for protection
efforts—The Ridge and North/Central Appalachian ecoregions.
If one uses a restoration strategy, and focuses on the subregions in the poorest condition, the
Valley, Western Appalachian, Piedmont and Coastal Plain ecoregions could all be targeted. Each
of these ecoregions has over 40% of the stream/river resource in poor condition for at least one
biological assemblage. Notice that these two strategies are mutually exclusive—no ecoregion
would be identified for both protection and restoration. Four out of six ecoregions are identified
by the restoration strategy, which is a not particularly helpful finding if our objective is to focus
the restoration effort, but it certainly does reinforce the idea that, overall, Mid-Atlantic flowing
waters are in trouble. If more stringent criteria are use—at least two of the three biological
assemblages must show greater than 40% of the stream resource in poor condition—then only
two subregions emerge as high priorities: the Coastal Plain and Western Appalachian ecoregions
(Figure 38). These more stringent criteria yield a more focused geographic target for restoration
efforts.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 56
-------
With what sorts of stressors are the Mid-Atlantics problems associated? Our analyses
indicate that excess sedimentation, increased nutrients, non-native fish species, and the absence
of large woody material in streams all pose significant relative risks, and are among the most
prevalent stressors throughout the region. Within the Coastal Plain, one of the two regions on the
potential priority list for restoration, several stressors should be considered: non-native fish,
excess sedimentation, and increased nutrients all represent significant relative risks and are found
extensively throughout the ecoregion. Within the Western Appalachian ecoregion, both excess
sediment and lack of large wood are widespread stressors associated with significant relative
risks. Mine drainage, while posing a somewhat lower relative risk, certainly is widespread within
the Western Appalachian ecoregion.
Coastal Plain Ecoregion
Poor Ecological Condition
Western Appalachians Ecoregion
Poor Ecological Condition
Fish
Macro-invertebrates
Algae
Introduced Fish
Sedimentation
Lack of Large Wood
Riparian Habitat
Mercury in Fish
Nitrogen
Phosphorus
Mine Drainage
Acidic Deposition
Organic Contaminants
Acid Mine Drainage
Stressors
Stressors
20 40 60 80
Percent of Stream Length
20 40 60 80 100
Percent of Stream Length
Figure 38. Combined results for two subregions that could be targeted for restoration
efforts—the Coastal Plain and Western Appalachian ecoregions.
The simple conclusions reached here are based on the kind of unbiased assessment that
probability monitoring can provide. Any environmental protection and restoration efforts are
likely to use these results as only one factor, among many, in making decisions on how to move
forward. Other considerations will include socio-economic and political factors, as well as
extensive public input on priorities. But all of these other factors can be more effectively
considered if environmental managers and the public are well informed about the state of the
environment—educated evaluation, based on unbiased scientific assessment, should be a key
ingredient in making sound environmental and economic decisions. Because of their importance,
similar environmental reports should become high priority precursors to the making of effective
environmental policies and decisions. We hope that the approach demonstrated here will help
guide the design of such future regional and national assessments.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page 57
-------
APPENDIX A: THRESHOLDS
Perhaps the most critical step in creating the kind of assessment presented in this report is
the setting of thresholds—how do we decide, in the most scientifically justifiable way, which
sites to place in Good, Marginal and Poor classes? As scientists, our role is to avoid being
judgmental, and letting our own opinions influence the labels we place on individual sites or
regions. We need an approach that relies entirely on data, not opinion, and lets the data "answer
the questions" about condition classes.
Throughout this report we use what is known as the "reference site approach" to identify
criteria. For nearly every variable (biological index, chemical concentration, or habitat index) we
identify a set of reference sites, and use the distribution of variable values for this set of sites to
define what "good" looks like. The only departures from this approach are for chemical variables
(like acid neutralizing capacity) whose values have special meaning—e.g., any ANC value less
than zero defines the class "acidic" chemically, and doesn't require any further classification.
We feel strongly that circular thinking, a common problem in any discussion of reference
condition, should be avoided at all costs. The most common way that circularity finds its way in
to the science or reference condition is through the use of biological data to identify reference
sites that are then used in interpreting the same biological data. This approach essentially asks,
"based on the biology, which are the best sites?", and then uses data from those "best" sites to
answer the question, "for the set of reference sites identified, how would I characterize the
biology?" For this reason, we choose to define "reference" differently for each index or variable
we want to classify, always avoiding the use of the variable itself (or elements of it, if the
variable is an index) to define reference condition. For example, if we want to classify scores for
our fish Index of Biotic Integrity, we need to avoid using any fish data to define which sites are
in reference condition.
The details of how we define "reference", as well as how we chose to use the reference
distribution to set thresholds, and how we incorporate potential ecoregional differences, are
presented below for each indicator used in this report. For each indicator where a reference site
approach is appropriate, we first identified the independent criteria that could be used to
determine reference condition, then examined the range of index or variable values that were
found in all of the sites meeting those criteria. Each of these exercises produced a distribution
like the one shown in Figure A-l. Once this distribution was established, we consistently used
the 25th percentile value to set the lower limit on "Good" condition. The 1st percentile was used
as the threshold below which values were deemed "Poor." Values between the 1st and 25th
percentiles were classified as "Marginal". In this hypothetical example, higher scores indicate
better condition—if an indicator worked in reverse (e.g., for phosphorus and nitrogen, higher
values indicate excess nutrients), we used the 75th and 99th percentile values in an exactly
analogous way to define the classes.
There is nothing magical about our choice of the 1st and 25th (or 99th and 75th) percentiles.
EMAP data allow us to set these thresholds anywhere within the distribution . We chose to be
consistent among all of the indicators we assess, and to use these thresholds because they have
some understandable statistical meaning. Sites we classify as in "Poor" condition for any given
MID-ATLANTIC FLOWING WATERS ASSESSMENT 1
-------
indicator have a greater than 99% probability of being outside of (or more extreme than) our
reference distribution. Sites classified as "Good" have a 75% probability of being within the
reference distribution. Many other thresholds are possible, and are in fact in use in other
programs. The 25th percentile is quite commonly used as a line separating "Good" from
"Marginal." Some bioassessments use the 5th, or even the 10th, percentile as a threshold to define
"Poor" condition, often invoking the argument that our knowledge of what constitutes
"reference" is imperfect and we are bound to include some sites in the reference distribution that
are not truly the least disturbed in a region. For this reason, it can be argued, it is reasonable for
some of the reference sites to have scores that we would label as "Poor." This is an issue that will
continue to be debated, but thus far there is no scientific consensus. We have chosen to use a
conservative estimate of the Marginal/Poor threshold because of its statistical power to define
what we mean by "Poor."
Reference Distribution
0)
0
0
CO
X
0
c
1 UU
90
80 -
70 -
60 -
50 -
/in
Percentiles:
o gg*11
" 95th
75*
50th 1
2gth Good
t
cih Ma rq, rial
0 ,
n -si *
1 Poor
Figure A-l. Example of the range of scores in reference sites (for a hypothetical indicator
or index), and percentile values of the reference distribution. In this assessment, we use the 25th
percentile as threshold between Good and Marginal condition, and the 1st percentile as the line
between Marginal and Poor condition.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page A-2
-------
MACROINVERTEBRATE INDEX OF BIOTIC INTEGRITY
IBI construction: We modified an Index of Biotic Integrity developed for the Mid-Atlantic
Highlands by Klemm et al. (2003), for use in the Mid-Atlantic region as a whole. We
examined the Klemm et al. metrics for responsiveness across the region, and eliminated one
(Plecoptera richness) because it does not respond well to human disturbances as Mid-
Atlantic streams become very large. The remaining metrics were re-scored and the final IBI
divided into classes according to the reference distribution. As in Klemm et al., different
metric scoring criteria were developed for pool-dominated streams and riffle-dominated
streams. One major concern in developing a Mid-Atlantic IBI for macroinvertebrates was
finding metrics that were responsive both in the uplands and in the Coastal Plain. Our final
list of metrics is very closely aligned with those of an IBI developed specifically for the
Coastal Plain by Maxted et al. (1999).
Reference definition: We used the process described by Waite et al. (2000) for the Mid-
Atlantic Highlands, to define reference sites for macroinvertebrates. The chemical and
physical variables used to identify candidate reference included ANC (non-acidic sites only),
sulfate (sites with no effects of mine drainage), phosphorus and nitrogen (no excess
nutrients), chloride (high chloride sites excluded—chloride is an indicator of general
watershed disturbance), and overall habitat quality (based on Rapid Bioassessment Protocol
[RBP] measures of habitat).
Thresholds: Based on the reference distribution, the classification thresholds for the MAIA
macroinvertebrate IBI were:
Classes
Macroinvertebrate IBI Thresholds
Good Condition
Marginal Condition
Poor Condition
62.25 < IBK 100
4KIBK62.25
0
-------
reference included ANC (non-acidic sites only), sulfate (sites with no effects of mine
drainage), phosphorus and nitrogen (no excess nutrients), chloride (high chloride sites
excluded—chloride is an indicator of general watershed disturbance), and overall habitat
quality (based on Rapid Bioassessment Protocol [RBP] measures of habitat).
Thresholds: Based on the reference distribution, the classification thresholds for the MAIA
algal IBI were:
Classes
Algal IBI Thresholds
Good Condition
Marginal Condition
Poor Condition
58
-------
IBI Threshold for:
Good Condition
Marginal Condition
Poor Condition
Upland
Streams
59 < IBI < 100
32 < IBI < 59
0
-------
ACID DEPOSITION
Index construction: We used ANC values for sites that had no indicators of mine drainage
(see above) to determine their status with respect to acid rain.
Thresholds: Sites unaffected by mine drainage were further classified by their ANC values:
sites with ANC < 0 were classified as chronically acidic; those with 0 < ANC < 50 jieq/L
were classified as being episodically acidic.
PHOSPHORUS
Index construction: We used measured values of total phosphorus as indicators of nutrient
enrichment in streams.
Reference definition: Reference sites were identified as those with less than 10% non-
natural land cover in their watersheds. Sites with more than 10% combined landuse classified
as urban, agricultural or mining were eliminated from the candidate reference list. A total of
317 sites met these criteria, but none were in the Coastal Plain. Because we were unable to
determine whether phosphorus thresholds that were appropriate for the rest of the Mid-
Atlantic were appropriate for the Coastal Plain, we used a separate approach for this
ecoregion. We used published EPA criteria (as used for the Mid-Atlantic Highlands—see
U.S. EPA 2000 report in Appendix C) for phosphorus in the Coastal Plain.
Thresholds (concentrations in |ig/L):
Phosphorus
Threshold for:
Non-Coastal Plain
Ecoregions
Coastal Plain Ecoregion
Good Condition
Marginal Condition
Poor Condition
0 < Total Phosphorus < 14 0 < Total Phosphorus ^50
14 < Total Phosphorus < 63 50 < Total Phosphorus < 100
Total Phosphorus > 63 Total Phosphorus > 100
NITROGEN
Index construction: We used measured values of total nitrogen as indicators of nutrient
enrichment in streams.
Reference definition: Reference sites were identified as those with less than 10% non-
natural land cover in their watersheds. Sites with more than 10% combined landuse classified
as urban, agricultural or mining were eliminated from the candidate reference list. A total of
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page A-6
-------
317 sites met these criteria, but none were in the Coastal Plain. Because we were unable to
determine whether nitrogen thresholds that were appropriate for the rest of the Mid-Atlantic
were appropriate for the Coastal Plain, we used a separate approach for this ecoregion.
Criteria developed for the Mid-Atlantic Highlands Report (see U.S. EPA 2000 in Appendix
C) were used in the Coastal Plain—the thresholds for phosphorus listed above for the Coastal
Plain were multiplied by 15 (the ratio of nitrogen to phosphorus in algae) to create nitrogen
criteria for this ecoregion.
Nitrogen Thresholds (concentrations in |ig/L):
Nitrogen Threshold
for:
Non-Coastal Plain
Ecoregions
Coastal Plain Ecoregion
Good Condition
Marginal Condition
Poor Condition
Total Nitrogen < 425 Total Nitrogen < 750
425 ^Total Nitrogen < 1200 750 ^Total Nitrogen < 1500
Total Nitrogen > 1200 Total Nitrogen > 1500
EXCESS SEDIMENT
Index construction: We used the "Relative Bed Stability Index" of Kaufmann et al. (1999)
as an indicator of excess fine sediments in streams. This index compares the observed mean
substrate size to each stream's expected substrate size, based on stream bed shear stress
during bank-full stage (calculated from stream size, slope, channel complexity, large wood
and bed armoring). Values of the sediment index range from negative to positive, with
theoretical expectations near values of zero.
Reference definition: Reference sites were identified as those meeting the same chemical
criteria as for the macroinvertebrate and algal indices, in addition to having good riparian
condition (see below). A total of 42 sites met these criteria. Because the Piedmont and
Coastal Plain ecoregions have much lower gradient streams than the regions for which
Kaufmann's bed stability index was developed, we were particularly concerned about
defining expectations for these ecoregions. Unfortunately, there were insufficient numbers of
reference sites in the Piedmont or Coastal Plain to determine whether thresholds needed to be
determined separately for these low-gradient ecoregions. Rather than apply an inappropriate
threshold, we chose to use the reference sites to set criteria for higher gradient ecoregions,
and best professional judgment to set criteria for the Piedmont and Coastal Plain.
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page A-7
-------
Sediment Thresholds:
Sediment Threshold
for:
Good Condition
Marginal Condition
Poor Condition
Non-Piedmont and Non-
Coastal Plain Ecoregions
Index > -0.3
-0.9 <_Index < -0.3
Index < -0.9
Piedmont and Coastal Plain
Ecoregions
Index > -1.5
-2.0<_Index<-1.5
Index < -2.0
LARGE WOODY MATERIAL
Index construction: We used areal estimates of wood in streams, collected according to the
EMAP stream and river protocols (see Lazorchak et al. references in Appendix C), as
indicators of large wood in streams. These estimates are calculated as the proportion of the
area of the wetted stream channel covered by wood, and vary from 0 to 1. Details of the
calculation of the index are covered in Kaufmann (1999).
Reference definition: Reference sites were identified as those with less than 10% non-
natural land cover in their watersheds, and with excellent riparian habitat (see below—we
used a riparian habitat index value of 0.8 or greater to identify excellent riparian habitat). A
total of 50 sites met these criteria.
Large Wood Thresholds (units are proportion of wetted stream area):
Classes
Good Condition
Marginal Condition
Poor Condition
Area of Large Wood (ALW)
Thresholds
2.2% < ALW < 100%
0% < ALW < 2.2%
ALW = 0%
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page A-8
-------
RIPARIAN HABITAT CONDITION
Index construction: We used the riparian habitat condition index described by Kaufmann et
al. (1999) as an indicator of the riparian condition of Mid-Atlantic flowing waters. This index
combines quantitative measures of the complexity of riparian vegetation (i.e., presence of
multiple layers of trees and shrubs), canopy cover, and visible human disturbances in the
riparian area. The index is unit-less and ranges from 0 to 1.
Reference definition: Reference sites were identified as those meeting the same chemical
criteria as for the macroinvertebrate and algal indices, in addition to expected amounts of fine
sediments (Bed Stability Index > -1; see discussion above), and little or no direct human
disturbance in the riparian area. A total of 31 sites met these criteria.
Riparian Habitat Index Thresholds:
Classes
Good Condition
Marginal Condition
Poor Condition
Riparian Habitat Index Thresholds
Index > 0.61
0.5 < Index < 0.61
Index < 0.5
MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page A-9
-------
CONTAMINANTS IN FISH
Index construction: Composite fish samples collected at each site (where possible); the goal
was to collect common species found throughout the MAIA region, and that are likely to be
abundant in a majority of streams. Crews attempted to collect two contaminant samples from
each stream reach: (1) a primary target species (species whose adults are small, such as
minnows, sculpins and darters); and (2) a secondary target species (species with large adults,
such as suckers, bass, trout, sunfish and carp). Details of sampling and sample handling can
be found in the MAIA field manual (Lazorchak et al. 1998). Mercury and organic
contaminant concentrations were measured in homogenized whole fish collected by these
methods.
Reference definition: Reference sites were not used in setting contaminant thresholds. We
instead used published threshold values based on wildlife risk from Lazorchak et al. (2003).
These thresholds were calculated specifically for the Mid-Atlantic region, based on toxicity
studies of commonly occurring wildlife species that rely almost exclusively on fish for their
diets. We chose to use the values for American River otter (see table below). Stream and
river sites were classified into one of three classes:
1. No fish collected (or no fish present)
2. Neither primary nor secondary target species exceeds American River otter criterion
("good" condition)
3. One or both fish samples (primary and secondary) exceeds American River criterion
for one or more contaminants ("poor" condition)
Thresholds: Wildlife criteria values for mercury and organic contaminants (reproduced
from Lazorchak et al. (2003); concentrations in |ig/g offish):
Contaminant
Mercury
Chlordane
DDT and metabolites
Dieldrin
PCBs
Detection Limits
0.025
0.002
0.002
0.002
0.002
Wildlife
Otter
0.10
1.14
0.49
0.03
0.18
values (|ig/g
Mink
0.07
0.83
0.36
0.02
0.13
offish)
Kingfisher
0.03
0.005
0.02
0.36
0.44
MID-ATLANTIC FLOWING WATERS ASSESSMENT Page A-10
-------
APPENDIX B: CALCULATING RELATIVE RISK
DEFINITION AND EXAMPLE CALCULATION
We define relative risk as the ratio of two probabilities:
Pr(Poor IBI score, given Poor Stressor Score)
Pr(Poor IBI Score, given Good Stressor Score)
where the numerator and denominator are conditional probabilities of a poor IBI score under
poor (numerator) vs. good (denominator) Stressor conditions.
As an example we calculate the relative risk of excess sediments for macroinvertebrates. We
begin by collecting together all sample sites having the same combinations of good and poor
condition for macroinvertebrate IBI and for sedimentation.
Sediment Condition
Number of Sites
Good Poor
, , . . A . Good 78 8
Macromverte orate
Condition „ cn ,,
Poor 50 55
Next, we estimate the total number of stream kilometers in each of the table's classes, by
summing the sampling weights for all of the sites in each class.
Sediment Condition
Estimated stream length
(km)
Good Poor
, , . , , , Good 22697.5 3934.1
Macromverte orate
Condition 27446.3 27678.7
The next step is to express the stream lengths as percentages of the total. The sum of stream
weights across all four classes is 81756.6 km. Only a small percentage of streams have Good IBI
when Sediment is Poor.
DRAFT MID-ATLANTIC FLOWING WATERS ASSESSMENT Page B-1
-------
Sediment Condition
% of Stream Length
Macroinvertebrate
Condition
Good
Poor
Sum
Good
27.8%
33.5%
61.3%
Poor
4.8%
33.9%
38.7%
Total: 100%
Now, we estimate the probability, or "risk", of a poor IB I, for poor sediment sites only, as
being equal to 33.9/38.7 = 0.876. Likewise, the risk of a poor IBI in streams with good sediment
conditions is given by 33.5/61.3 = 0.546. Comparison of these two risks shows that a poor IBI
has a greater risk of occurring when sediment conditions are poor (risk = 0.876) then when
sediment conditions are good (risk = 0.546).
The relative risk ratio expresses this relationship in a single number, the ratio of the poor-
stressor IBI risk to the good-stressor IBI risk—that is, the relative risk = 0.876/0.546 = 1.60.
The way we interpret this number in this assessment is that a poor IBI is 1.60 times more
likely to occur when sediment conditions are poor than when they are good.
CONFIDENCE INTERVALS FOR RELATIVE RISK
We used large-sample approximations to construct confidence intervals for relative risk
(RR). Large-sample distributions for estimated RR are better approximated using the log
transformation to produce symmetry about the null value of 1.0, and to ensure that confidence
bounds remain within the domain of the estimated parameter (see Lachin reference in Appendix
C). Given an estimate of the standard error for the estimated log(RR), percentiles of the standard
normal distribution were then used to construct a conventional large-sample confidence interval
for log(RR). Finally, interval endpoints were back-transformed to give the corresponding
confidence interval for RR.
To estimate the standard error of log(RR), we used a Taylor linearization method (see
Sarndal et al. reference in Appendix C), which accounts for the unequal inclusion probabilities of
the MAIA sampling design.
DRAFT MID-ATLANTIC FLOWING WATERS ASSESSMENT
Page B-2
-------
APPENDIX C: FURTHER READING
ENVIRONMENTAL MONITORING AND ASSESSMENT
PROGRAM
Environmental Monitoring and Assessment Program website: http://www.epa.gov/emap2/
Stevens Jr., D.L. 1994. Implementation of a national monitoring program. Journal of
Environmental Management 42:1-29.
Paulsen, S.G., R.M. Hughes, and D.P. Larsen. 1998. Critical elements in describing and
understanding our nation's aquatic resources. Journal of the American Water Resources
Association 34:995-1005.
Hughes, R.M., J.L. Stoddard, and S G. Paulsen. 2000. A national, multiassemblage, probability
survey of ecological integrity. Hydrobiologia 422/423:429-443.
Landers, D.H., R.M. Hughes, S.G. Paulsen, D.P. Larsen, and J.M. Omernik. 1998. How can
regionalization and survey sampling make limnological research more relevant?
Verhandlungen Internationale Vereinigung Limnologie 26:2428-2436.
Lazorchak, J.M., B.H. Hill, O.K. Averill, D.V. Peck, and D.J. Klemm, editors. 2000.
Environmental Monitoring and Assessment Program-Surface Waters: Field Operations
and Methods for Measuring the Ecological Condition of Non-Wadeable Rivers and
Streams. U.S. Environmental Protection Agency, Cincinnati, OH.
Lazorchak, J.M., D.J. Klemm, and D.V. Peck. 1998. Environmental Monitoring and Assessment
Program-Surf ace Waters: Field Operations and Methods for Measuring the Ecological
Condition of Wadeable Streams. EPA/620/R-94/004, U.S. Environmental Protection
Agency, Washington, DC.
SAMPLE SURVEY DESIGN
Herlihy, A.T., D.P. Larsen, S.G. Paulsen, N.S. Urquhart, and B.J. Rosenbaum. 2000. Designing a
spatially balanced, randomised site selection process for regional stream surveys: The
EMAP Mid-Atlantic Pilot Study. Environmental Monitoring and Assessment 63:95-113.
Olsen, A.R., J. Sedransk, D.Edwards, C.A. Gotway, W. Liggett, S. Rathbun, K.H. Reckhow, and
L.J. Young. 1999. Statistical issues for monitoring ecological and natural resources in the
United States. Environmental Monitoring and Assessment 54:1-45.
Stevens Jr., D.L. 1997. Variable density grid-based sampling designs for continuous spatial
populations. Environmetrics 8:167-195.
Stevens Jr., D.L., and A.R. Olsen. 1999. Spatially restricted surveys over time for aquatic
resources. Journal of Agricultural, Biological, and Environmental Statistics 4:415-428.
DRAFT MID-ATLANTIC FLOWING WATERS ASSESSMENT Page C-1
-------
Stevens Jr., D.L., and N.S. Urqhart. 2000. Response designs and support regions in sampling
continuous domains. Environmetrics 11:11-41.
ECOLOGICAL REGIONS
Omernik, J.M. 1987. Ecoregions of the conterminous United States. Annals of the Association of
American Geographers 77:118-125.
Woods, A.J., J.M. Omernik, D.D. Brown, and C.W. Kiilsgaard. 1996. Level III and IV
Ecoregions of Pennsylvania and the Blue Ridge Mountains, the Ridge and Valley, and
the Central Appalachians of Virginia, West Virginia, and Maryland. EPA/600R-96/077,
U.S. Environmental Protection Agency, National Health and Environmental Effects
Research Laboratory, Corvallis, OR.
BIOTIC INTEGRITY
Hill, B.H., A.T. Herlihy, P R. Kaufmann, R J. Stevenson, F.H. McCormick, and C. Burch
Johnson. 2000. Use of periphyton assemblage data as an index of biotic integrity. Journal
of the North American Benthological Society 19:50-67.
Hughes, R.M., P.R. Kaufmann, A T. Herlihy, T.M. Kincaid, L. Reynolds, and D P. Larsen. 1998.
A process for developing and evaluating indices of fish assemblage integrity. Canadian
Journal of Fisheries and Aquatic Science 55:1618-1631.
Hughes, R.M., D.P. Larsen, and J.M. Omernik. 1986. Regional reference sites: A method for
assessing stream potentials. Environmental Management 10:629-635.
Karr, J.R. 1981. Assessment of biotic integrity using fish communities. Fisheries 6:21-27.
Karr, J.R., and E.W. Chu. 1997. Biological monitoring and assessment: using multimetric
indexes effectively. EPA/235/R97/001, University of Washingon, Seattle, WA.
Karr, J.R., and D.R. Dudley. 1981. Ecological perspective on water quality goals. Environmental
Management 5:55-68.
Klemm, D.J., K.A. Blocksom, F. A. Fulk, A.T. Herlihy, R. M. Hughes, P.R. Kaufmann, D.V.
Peck, J.L. Stoddard, and W.T. Thoeny. 2003. Development and evaluation of a
macroinvertebrate biotic integrity index (MBII) for regionally assessing Mid-Atlantic
Highlands streams. Environmental Management 31:656-669.
Larsen, D.P., and AT. Herlihy. 1998. The dilemma of sampling streams for macroinvertebrate
richness. Journal of the North American Benthological Society 17:359-366.
Maxted, J., M.T. Barbour, J. Gerritsen, V. Poretti, N. Primrose, A. Silvia, D. Penrose, and R.
Renfrow. 1999. Assessment Framework for Mid-Atlantic Coastal Plain Streams Using
Benthic Macroinvertebrates. NHEERL-NAR-X-255, U.S. Environmental Protection
Agency, Narraganset, RI.
DRAFT MID-ATLANTIC FLOWING WATERS ASSESSMENT Page C-2
-------
McCormick, F.H., R.M. Hughes, P.R. Kaufmann, D.V. Peck, J.L. Stoddard, and A.T. Herlihy.
2001. Development of an index of biotic integrity for the Mid-Atlantic Highlands region.
Transactions of the American Fisheries Society 130:857-877.
Pan, Y., RJ. Stevenson, B.H. Hill, and A.T. Herlihy. 2000. Ecoregions and benthic diatom
assemblages in Mid-Atlantic Highlands streams, USA. Journal of the North American
Benthological Society 19:518-540.
Pan, Y., RJ. Stevenson, B.H. Hill, P.R. Kaufmann, and A.T. Herlihy. 1999. Spatial patterns and
ecological determinants of benthic algal assemblages in Mid-Atlantic Highlands streams.
Journal of Phycology 35:460-468.
Plafkin, J.L., M.T. Barbour, K.D. Porter, S.K. Gross, and R.M. Hughes. 1989. Rapid
Bioassessment Protocols for Use in Streams and Rivers. EPA/440/4-89/001, U.S.
Environmental Protection Agency, Washington DC.
Roth, N.E., M.T. Southerland, J.C. Chaillou, RJ. Klauda, P.P. Kazyak, S.A. Stranko, S.B.
Weisberg, L.W. Hall, Jr.,, and R.P. Morgan II. 1998. Maryland biological stream survey:
Development of a fish index of biotic integrity. Environmental Monitoring and
Assessment 51:89-106.
Waite, I.R., A.T. Herlihy, D.P. Larsen, and DJ. Klemm. 2000. Comparing strengths of
geographic and nongeographic classifications of stream benthic macroinvertebrates in the
Mid-Atlantic Highlands, USA. Journal of the North American Benthological Society
19:429-441.
U.S. Environmental Protection Agency. 1996a. Biological Criteria: Technical Guidance for
Streams and Small Rivers. EPA/822/B-96/001, U.S. Environmental Protection Agency,
Washington, DC.
STRESSORS
Baker, L.A., A.T. Herlihy, P.R. Kaufmann, and J.M. Eilers. 1991. Acidic lakes and streams in
the United States: The role of acidic deposition. Science 252:1151-1154.
Herlihy, A.T., P R. Kaufmann, M E. Mitch, and D.D. Brown. 1990. Regional estimates of acid
mine drainage impact on streams in the mid-Atlantic and southeastern United States.
Water Air and Soil Pollution 50:91-107.
Herlihy, A T., J.L. Stoddard, and C.B. Johnson. 1998. The relationship between stream
chemistry and watershed land use data in the Mid-Atlantic region, U.S. Water Air and
Soil Pollution 105:377-386.
Kaufmann, P.R., P. Levine, E.G. Robison, C. Seeliger, and D. Peck. 1999. Quantifying Physical
Habitat in Wadeable Streams. EPA/620/R-99/003, U.S. EPA, Washington, D.C.
DRAFT MID-ATLANTIC FLOWING WATERS ASSESSMENT Page C-3
-------
Lazorchak, J.M., F.H. McCormick, T.R. Henry, and A.T. Herlihy. 2003. Contamination offish
in streams of the Mid-Atlantic Region: an approach to regional indicator selection and
wildlife assessment. Environmental Toxicology and Chemistry 22:545-553.
RELATIVE RISK
Lachin, J.M. 2000. Biostatistical Methods: The Assessment of Relative Risk. John Wiley and
Sons, New York.
Sarndal, C.E., B. Swensson, and J. Wretman. 1992. Model-assisted Survey Sampling. Springer-
Verlag, New York.
OTHER MID-ATLANTIC ASSESSMENTS
Mid-Atlantic Integrated Assessment website: http://www.epa.gov/maia/
Ator, S.W., and MJ. Ferrari. 1997. Nitrate and selected pesticides in ground water of the Mid-
Atlantic region. U.S.G.S. Water Resources Investigations Report 97-4139.
Boward, D., P. Kayzak, S. Stranko, M. Kurd, and A. Prochaska. 1999. From the Mountains to
the Sea: The State of Maryland's Freshwater Streams. EPA/903/R-99/023, U.S.
Environmental Protection Agency, Philadelphia, PA.
Bryce, S.A., D.P. Larsen, R.M. Hughes, and P R. Kaufmann. 1999. Assessing the relative risks
to aquatic ecosystems in the Mid-Appalachian region of the United States. Journal of the
American Water Resources Association 35:23-36.
Hill, B.H., A.T. Herlihy, P.R. Kaufmann, and R.L. Sinsabaugh. 1998. Sediment microbial
respiration in a synoptic survey of Mid-Atlantic streams. Freshwater Biology 39:493-501.
Jones, K.B., K.H. Riitters, J.D. Wickham, R.D. Tankersley, R. V. O'Neill, D.J. Chaloud, E.R.
Smith, and A.C. Neale. 1997. An Ecological Assessment of the United States Mid-
Atlantic Region: A Landscape Atlas. EPA/600/R-97/130, U.S. Environmental Protection
Agency, Washington, DC.
U.S. Environmental Protection Agency. 1998. Condition of the Mid-Atlantic Estuaries.
EPA/600/R-98/147 U.S. Environmental Protection Agency, Washington, DC.
U.S. Environmental Protection Agency. 2000. Mid-Atlantic Highlands Streams Assessment.
EPA/903/R-00/015, U.S. Environmental Protection Agency, Region 3, Philadelphia, PA.
(available at: http://www.epa.gov/maia/html/maha.html)
ENVIRONMENTAL REPORT CARDS
H. John Heinz III Center for Science, Economics, and the Environment. 2002. The State of the
Nation's Ecosystems: Measuring the Lands, Waters, and Living Resources of the United
States. Cambridge University Press, Cambridge, UK.
DRAFT MID-ATLANTIC FLOWING WATERS ASSESSMENT Page C-4
-------
U.S. Environmental Protection Agency. 2003. Draft Report on the Environment. EPA 260-R-02-
006, U.S. Environmental Protection Agency, Washington, DC.
DRAFT MID-ATLANTIC FLOWING WATERS ASSESSMENT Page C-5
------- |