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From the Mountains to the Sea:
The State of Maryland's Freshwater Streams
Authors
Daniel Boward, Paul Kazyak, Scott Stranko
Martin Hurd, Anthony Prochaska
Maryland Department of Natural Resources
Tawes State Office Building, C-2
580 Taylor Avenue
Annapolis, MD 21401
with support from
United States Environmental Protection Agency
National Health and Environmental Effects Research Laboratory
Atlantic Ecology Division
27 Tarzwell Drive
Narragansett, RI02882
and
Region III
Environmental Services Division
1650 Arch Street
Philadelphia, PA 19103
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NOTICE
The information in this report was funded hi part by the United States Environmental Protection
Agency (Environmental Monitoring and Assessment Program, Office of Research and Develop-
ment) through the Atlantic Ecology Division. Support was provided to the Maryland Department
of Natural Resources by EPA Cooperative Agreement #CR-825488-01-0, T. Pheiffer, Project
Officer. The report was subjected to the EPA's peer and administrative review, and has received
approval for publication as an EPA document. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
The suggested citation for this report is: D.M. Boward, P.P. Kazyak, S.A. Stranko, M.K. Hurd,
andTP. Prochaska. 1999. From the Mountains to the Sea: The State of Maryland's Freshwater
Streams. EPA 903-R-99-023. Maryland Department of Natural Resources, Monitoring and Non-
tidal Assessment Division, Annapolis, Maryland.
ABSTRACT
The Maryland Biological Stream Survey, conducted by the Maryland Department of Natural
Resources, sampled about 1,000 randomly-selected sites on first through third order freshwater
streams throughout Maryland from 1995 to 1997. Biota (fish, benthic macroinvertebrates,
herpetofauna) and water chemistry were sampled and physical habitat quality was assessed at
each site. Land use/land cover in the watershed upstream of each site was also determined. This
report is intended to present the results of the Survey to a broad array of audiences, including the
general public, about the condition of wadeable freshwater streams in Maryland. The report is
also intended to serve as a tool for resource managers and planners for developing policy and
targeting areas for restoration and preservation. For example, the report describes the impact of
urbanization on fish and benthic macroinvertebrate communities (using indices of biotic integ-
rity), herpetofauna, and stream temperatures. These findings should be useful for land use plan-
ning in areas of the state slated for development. The report also describes the extent of physical
habitat degradation, including riparian buffer conditions. Other topics include acidification;
nutrient enrichment; biodiversity; introduced fish; and rare, threatened, and endangered fish
species. The reader is provided with a historical context in which to view the current health of
Maryland's streams. Suggestions are included on how individuals can work with organizations to
protect and restore their local streams.
KeyWords: Streams; Maryland; Chesapeake Bay; Environmental Monitoring; Ecological Assess-
ment; River Basin; Watershed; Aquatic Life; Biological Diversity; Biological Indicators; Water
Quality; Physical Habitat
it
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greetings from the Maryland department
of Natural Resources and the
V.S. (Environmental"(protection Agency
Dear Reader:
Maryland's streams represent a vital, life-giving resource to its citizens. In
addition to providing clean water to support life in Chesapeake Bay, the world's most
productive estuary, our streams provide habitat for a multitude of plants and
animals. From cascading mountain brooks to meandering coastal streams, flowing
waters are sought out for their great beauty, recreational value, and source of tranquility
in a fast-paced world. For these reasons and more, protection and restoration of our aquatic
world need to be high on our list of priorities.
Because the health of our streams reflects conditions on the lands that they drain, the health of
our aquatic life is very much dependent on the health of our watersheds. What is the current
condition of our streams? Which human activities have the most effect on our streams and
where are these activities most pronounced? This report begins to answer these types of ques-
tions using information from the Maryland Biological Stream Survey, or MBSS, developed by
the Maryland Department of Natural Resources and supported by the U.S. Environmental
Protection Agency.
Maryland is working on stream protection in a variety of ways. Governor Parris N.
Glendening's nationally acclaimed Smart Growth and Neighborhood Conservation initiative
recognizes the link between how we develop our land and the quality of our waterways. By
financially supporting new growth only in existing communities or areas locally designated for
growth, and by permanently preserving forested buffers and other valuable land through the
new Rural Legacy Program, the Smart Growth initiative bolsters efforts to keep Maryland
streams clear and clean.
In the past, water monitoring programs have focused largely on the chemical make-up of our
streams. With the MBSS, Marylanders can be proud that the state is leading the way in provid-
ing a state-of-the-art assessment and management tool for our streams. By embracing the new
science of ecological assessment and combining information on water chemistry, physical
habitat, and aquatic life, we have gained a more realistic picture of the health of our streams,
and we are proud to share some of our findings with you. By providing you with this first of a
new generation of reports on Maryland's streams, we hope to spur your interest in streams and
lead you to an increased awareness and involvement in the protection and restoration of these
irreplaceable natural resources.
Parris N. Glendening
Governor
State of Maryland
Michael McCabe
Acting Deputy Administrator
U.S. Environmental Protection Agency
Deer Creek in
the Susquehanna
River basin.
Photo courtesy
ofMD DNR
iii
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From the Mountains
to the Sea...
The State of
Maryland's
Freshwater Streams
This report was produced by the Maryland
Department of Natural Resources (MD DNR),
Resource Assessment Service, Monitoring and
Non-tidal Assessment Division, through
Cooperative Agreement Number CR-825488-
01-0 from U.S. EPA Office of Research and
Development.
Authors: Daniel Boward, Paul Kazyak, Scott
Stranko, Martin Kurd, and Anthony Prochaska
Contributors: We wish to thank several
people for their valuable contributions to this
report. First, the following people contributed
greatly to this report by managing and analyz-
ing data and working to develop the indicators
used here: Mark Southerland, Nancy Roth, and
Janis Chaillou of Versar, Inc.; Sam Stribling,
Jeffrey White, and Ben Jessup of Tetra Tech,
Inc.; and Ray Morgan and Lenwood Hall of
the University of Maryland.
We also wish to thank Ron Klauda, Paul
Massicot, Ceil Petro, William Jenkins, Robert
Lundsford, Ray Dintamin, Frank Dawson,
John McCoy, Larry Lubbers, and Ken Yetman
Big Elk Creek in the Elk River basin
Photo courtesy ofMD DNR
of DNR; Tom Pheiffer, Pat Bradley, Tom
DeMoss, Steve Paulsen, Chuck Kanetsky,
Maggie Passmore, and John Stoddard of U.S.
Environmental Protection Agency; Ron
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Acknowledgements
Preston of the Canaan Valley Institute; Karl
Blankenship of the Alliance for the Chesa-
peake Bay; Paul Angermeier of the U.S.
Geological Survey, and Tom Simpson of the
Maryland Department of Agriculture for
reviewing the report. Last, but certainly not
least, we thank Ray Morgan, Lenwood Hall,
Matt Klein, and Bill Killen of the University of
Maryland for data collection and Derek Wiley,
John Stavlas, Natasha Davis, Ann Lenert, Dung
Nguyen, and Lamar Platt of DNR for data
analysis and presentation.
This report has been reviewed and approved
for publication by the U.S. Environmental
Protection Agency. Approval does not signify
that the contents necessarily reflect the views
and/or policies of the EPA. Mention of trade
names, products, or services does not convey,
and should not be interpreted as conveying,
official EPA approval, endorsement, or
recommendation.
On the cover: Hunting Creek
tumbles over Cunningham
Falls in Western Maryland
vi
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Greetings from Maryland Department of Natural Resources and
the U.S. Environmental Protection Agency iii
Acknowledgements v
Highlights 1
Introduction 5
Geographic Setting 6
How Have our Streams Changed Since European Settlement? 8
This Report 9
The State of Maryland's Freshwater Streams , 11
Water Quality 13
Nutrients , 13
Acidity ; 15
Dissolved Oxygen 18
Water Temperature 18
Physical Habitat 21
Riparian Zones 21
Wood in Streams 22
Channelization 23
Bank Stability -, 25
Overall Habitat Quality 26
Aquatic Life 27
Reptiles and Amphibians 27
VII
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Table of Contents
viii
Fish 29
General Description 29
Introduced Fish 29
A Tale of Two Natives 31
Rare, Threatened, and Endangered Fish Species 33
Benthic Macroinvertebrates 35
Index of Biotic Integrity , 37
The Future of Maryland's Streams 38
It Will Take Teamwork 40
Glossary 43
Technical Appendix 47
For More Information 52
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The purpose of this report is to begin to
address the current health of
Maryland's freshwater streams and to
determine the impacts of human activities on these
waters. The data base compiled for this report will
also be used in the preparation of Maryland's next
biennial water quality report to Congress. "With the
availability of this new statewide information, a
logical next step will be to evaluate it's applicabil-
ity to regulatory activities. A multi-agency effort is
now underway in Maryland to determine how
these data on the State's streams can be used to
develop biocriteria for water quality regulatory
programs (see "The Future of Maryland's
Streams" section).
Below are the major findings from three years of
stream sampling (1995-1997) by the Maryland
Biological Stream Survey (MBSS...or the
Survey). Data from about 1,000 randomly-
selected sites were used to assess Maryland's
non-tidal freshwater streams from the Appala-
chian Mountains of Garrett County to the Lower
Eastern Shore. Aquatic animals (fish, benthic
macroinvertebrates, reptiles, and amphibians),
physical habitat, and water chemistry were
assessed at each site, as well as land use in the
upstream watershed. Indices of Biotic Integrity
for fish and benthic macroinvertebrates were
used to tell us the overall ecological health of the
sampled streams. For the first time, we now have
a comprehensive and scientifically-defensible
tool for telling us how many stream miles, either
within certain river basins or statewide, are
healthy or not. This tool also gives us insight into
some of the causes of stream degradation. For a
detailed description of the design and methods
used by the Survey, see the Technical Appendix
at the end of this report.
Land Use Impacts
Current patterns of urbanization have caused
significant impacts to Maryland's streams. If
urban sprawl continues to consume our forests
and farmlands in the same manner as in the
past, more Maryland streams will likely
degrade in the years to come. For example, the
health of many streams is largely influenced
by the amount of impervious land cover
upstream. Three indicators of stream health
help us illustrate the harmful effects of urban-
ization on stream biota. When watershed
imperviousness exceeds 25%, only hardy,
pollution-tolerant reptiles and amphibians can
thrive, while more pollution-sensitive species
are eliminated. Above 15% watershed imper-
viousness, stream health is never rated good,
based on a combined fish and benthic
macroinvertebrate Index of Biotic Integrity.
Even low levels of imperviousness affect
streams. When upstream impervious land
cover is above 2%, pollution-sensitive brook
trout are never found. Streams most affected
by urbanization are in the Baltimore-Washing-
ton Metropolitan portions of the Patapsco and
Potomac Washington Metro river basins.
Urbanization
continues to
threaten
Maryland
streams. If the
current rate of
urban sprawl
continues, more
Maryland
streams will
likely degrade.
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Highlights
More than half
of Maryland's
stream miles
have un-
naturally
elevated
nutrient levels.
These levels
are generally
highest in
watersheds
with more
agricultural
land use.
Physical
habitat
degradation is
the most
widespread
source of
stress on
Maryland's
streams, and is
extensive in
all but one
river basin.
% IMPERVIOUS COVER
The primary and most widespread source of
nutrients in streams is runoff from farm fields,
although excess nutrients enter streams from
several other sources, such as acid rain, lawns,
golf courses, and septic systems. About 57% of
the state's stream miles have unnaturally el-
evated nutrient concentrations, and these
concentrations are generally higher in water-
sheds with more agricultural land use. Some
sites with greater than 50% agricultural land use
upstream contain nitrate concentrations as high
as 24 mg/L. Two heavily farmed river basins—
the Chester and Middle Potomac—have several
streams with very high nitrate concentrations.
Although excess nitrate in small streams may
produce an overabundance of algae and aquatic
plants, the greatest impacts are realized down-
stream in tidal rivers and Chesapeake Bay.
Habitat Loss
The loss of high-quality physical habitat is
widespread in Maryland streams due to many
factors, such as elimination of forested riparian
(streamside) buffers and channelization. Only
20% of all stream miles in Maryland have good
physical habitat quality, while 52% are in poor
condition. More than one-quarter (27%) of
Maryland's stream miles have no vegetated
riparian buffers and thus are poorly protected
against stormwater runoff. Because forested
buffers are a key component of healthy streams
and a healthy Chesapeake Bay, we need to
replant those streamside forests that have been
lost and redouble our efforts to protect those
that remain.
About 17% of all stream miles statewide are
channelized. Channelized streams are un-
healthy for several reasons, including poor
habitat and elevated water temperatures. They
also serve to transport sediment, nutrients, and
pollutants to the Chesapeake Bay more rapidly
than streams with natural meandering channels
and healthy biota.
This urban stream channel has been drasti-
cally altered to increase stormwater drainage.
Photo by Paul Kazyak
Because of the more than 1,000 migration
barriers across Maryland streams and rivers,
much of the stream habitat once available to
migratory fish is now unaccessible. For
example, American eel populations have been
diminished by these migration barriers.
Acidity
Acid rain is the most important and most
widespread source of acidity in Maryland
streams, affecting nearly one-fifth of the state's
stream miles. Natural acidification and acid
mine drainage each acidify about 3% of all
stream miles, while runoff of fertilizers acidi-
fies about 4%. Low stream pH has a dramatic
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Highlights
effect on fish. While streams with pH greater
than 6 have more than 9,000 fish per stream
mile, those with pH less than 5 contain no fish.
Biological Health
Based on a combined fish and benthic
macroinvertebrate Index of Biotic Integrity,
about 12% of all stream miles in Maryland are in
good condition, 42% are fair, and almost one-
half (46%) are poor. Poor streams are considered
unhealthy compared to reference (healthiest)
streams. Good and fair streams are considered
healthy compared to reference streams. Good
streams are comparable to the highest quality
reference streams and fair streams are compa-
rable to the remainder of the reference streams.
These two communities of stream animals give
us valuable insights into cumulative impacts
(such as acid rain, urban and agricultural runoff,
and point source discharges) on our streams.
Biological Diversity
In spite of the many stressors on Maryland's
streams, they still harbor an incredible diversity of
animal life. For example, 45 species of amphib-
ians and reptiles occupy Maryland streams, with
91 % of all stream miles having at least one
species. About 350 types of benthic
macroinvertebrates live among the rocks, roots,
wood, sand, and mud of Maryland's streams
where they process nutrients and provide food for
fish, birds, and mammals.
The southern leopard frog is among the 45
species of reptiles and amphibians found in
and along Maryland streams during the
Survey.
Photo by Brian Stranko
About 100 fish species swim in Maryland
streams—the most abundant is the pollution
tolerant blacknose dace. Six fish species are listed
as rare, threatened or endangered and an addi-
tional 14 species were found during the Survey at
only a few locations. These species may be at risk
and are thus candidates for future listing.
Summary of
Stressors
Results of the Survey can help answer impor-
tant management questions about the relative
impacts and geographic extent of different
stressors on Maryland streams (Table 1). The
most extensive and widespread source of
stress is physical habitat degradation, which is
extensive in all but one of Maryland's river
basins (Elk River). Inadequate riparian buffers,
unstable stream banks, and channelization all
contribute to physical habitat degradation.
Major water quality stressors include excess
nutrients, acid rain, and acid mine drainage.
Acid rain is an extensive problem, primarily in
Western Maryland and on the Lower Western
Shore, while acid mine drainage problems are
confined to Western Maryland.
There are many stressors that degrade
Maryland's streams. Together, we can all
help protect those that are still healthy.
Photo courtesy ofMD DNR
Based on the
health of fish
and benthic
macroin-
vertebrate
communities,
only about one
in ten miles of
streams are in
good condition,
while about
half are poor.
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Highlights
Tfcble 1. Summary of key stressors to Maryland's freshwater streams by major river basin. Colors represent the
best estimate of the severity and extent of each stressor. Red and yellow indicate severe and moderate stress,
respectively. No color indicates relatively little impact from a stressor within a basin.
Chann4lizatioiii Poor
i Overall
: Physical
I , Habitat
North Branch
Potomac
Potomac
Wash/Metro
Nanticoke/
Wicomico
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With the Appalachian Mountains to
the west and the beaches of the
Atlantic Ocean to the east, Mary-
land is a state of geographic diversity. Often
called "America in Miniature," it is 12,189
square miles of rugged mountains, fertile
valleys, rolling hills, and coastal flatlands. It is
also a mosaic of landscapes. Forests, farm
fields, suburbs, and dense urban areas are
found throughout the state. And in the center
of it all is Chesapeake Bay...one of Maryland's
most precious natural resources and a true
national treasure.
Maryland's freshwater streams mirror this
diversity. From the cascading rapids of Muddy
Creek Falls in Garrett County, to the sluggish
blackwater* of Zekiah Swamp in Charles
County, our more than 8,800 miles of freshwa-
ter streams are a valuable resource for us all.
They are the lifeblood of the land around us.
They connect our backyards, shopping malls,
and farm fields with the Bay and the ocean.
Our streams provide us with drinking water,
places to swim, fish, canoe, or places to
simply stop and contemplate, away from the
bustle of daily life. In large measure, they also
determine the health of Chesapeake Bay.
In addition to their values to humans, many of
our streams are biological wonderlands—with
myriad species of aquatic plants and animals
that often go unseen to all but the most astute
observer. In swiftly-moving water, sluggish
snails scrape tiny colonies of microscopic
protists from rocks. In deep, dark pools,
shrimp-like amphipods nibble last fall's maple
leaves, producing detritus for downstream
food webs. In a nearby mass of submerged
tree roots, a crafty predatory dragonfly larva
pounces on and consumes an unsuspecting
mayfly...only to be consumed itself by a
Maryland's Diverse Streams.
On its way to the Youghiogheny River
in Garrett County, Muddy Creek Falls
tumbles through Swallow Falls State
Park (right). Worcester County's
Nassawango Creek (left) meanders to
the Pocomoke River.
Photo by Brian Stranko (left) and
courtesy ofMD DNR (right)
*terms in the glossary are highlighted at first usage
Most
Marylanders
live within a
15 minute walk
of a stream.
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Introduction
Ninety-five
percent of
Maryland's
streams
flow into
Chesapeake
Bay. Some
streams flow
either toward
the Gulf of
Mexico or
through the
Coastal Bays
to the Atlantic
Ocean.
voracious brook trout. The trout, of course,
may end up as a delicious human dinner.
Scenes like these occur every day in many of
our streams and we humans play an increas-
ingly large part in directing them; for it is how
we live our lives that determines the health of
the streams around us.
Before we begin our evaluation of the health
of Maryland's streams, we must first under-
stand the natural diversity of lands within the
state and how we humans have altered the
land to suit our purposes. Because streams
may be quite different depending on their
location, we will examine how geology and
terrain vary across the state and the many
impacts resulting from human activities.
Geographic Setting
Maryland is divided into three broad geo-
graphic areas (Figure 1): the Appalachian
Plateau, Piedmont, and Coastal Plain prov-
inces. Each has its own combination of soils,
geology, vegetation, and terrain that function
together to produce different stream types. To
the east, the flat, low-lying Eastern Shore and
the rolling uplands of the Western Shore make
up the Coastal Plain. This area envelops the
What is the Fall Line?
A line roughly along Interstate 95 joining
lareas of relatively steep gradient on several
rivers on Maryland's western shore. The line ;
marks the geographical area where each river
descends from the hilly Piedmont to the flat
and sandy Coastal Plain. It also marks the
limit of upstream commercial navigation,
which, from an historical perspective,
explains why most Marylanders live and
work along this corridor.
Chesapeake Bay and has soils of sand, silt, or
clay and slow-flowing streams with soft sand
or gravel bottoms. The Coastal Plain is
separated from the remainder of the state by
the Fall Line, directly west of which are the
undulating hills of the Piedmont. Most Pied-
mont streams are of moderate slope, with rock
or bedrock bottoms. West of the Piedmont, the
geographically diverse Appalachian Plateau
(composed of the Blue Ridge, Valley and
Ridge, and Allegheny Plateau) has expansive
limestone-rich valleys, broadly sloping
mountains, and high, steep ridges. Streams in
the Appalachian Plateau are mostly rocky and
may meander through wide floodplains or
Valley and Ridge
'Allegheny
figure 1. Maryland has 3 broad geographic areas: the Coastal Plain, Piedmont, and
Appalachian Plateau. The Appalachian Plateau has the most diverse landscape.
6
-------
Introduction
cascade down steep mountainsides. Yet even in
these mountainous areas, some streams course
through wetland glades and take on much the
same character as their Eastern Shore counter-
parts.
On a finer scale, Maryland is divided into 18
large river basins—the geographic areas of
interest for this report—each containing an
intricate network of streams (Figure 2). The
Middle Potomac basin is the largest of these
basins, with 925 square miles and 1,102 stream
Maryland is also a mosaic of land uses. Today,
only 42% of the state is forested (Figure 3)
while prior to European settlement, more than
90% of the state was forested. The most
heavily forested river basins are the North
Branch Potomac and Youghiogheny in Western
Maryland. Most of the state's remaining
wetlands (about 8% of the total area) are
concentrated on the Lower Eastern Shore. A
little more than one third (34%) of Maryland's
land is used for fanning. The Chester and
Middle Potomac river basins are both more
Chesapeake Bay
h Figure 2. Maryland has 18 large river basins. All but two, the Youghiogheny and Ocean
f Coastal, flow to the Chesapeake Bay. Because it contains few non-tidal, freshwater streams,
[-Survey information from the Ocean Coastal basin is not included in this report.
miles. The Bush basin is the smallest, with just
195 square miles and 186 stream miles. Some
basins like the Patuxent and Patapsco lie
completely within Maryland, but most extend
beyond Maryland into Pennsylvania, Delaware,
or West Virginia. By examining stream health
within river basins, we provide a tool for
assessing the effectiveness of watershed
management programs such as Maryland's
Tributary Strategies. We also can target certain
areas of the state for stream protection and
restoration programs and develop a standard
geographic unit for assessing trends in stream
health over the years to come.
than one-half farmland. Urban and suburban
land (residential, commercial, industrial,
institutional, and extractive) make up about
16% of Maryland and are concentrated in the
Washington-Baltimore metropolitan area,
primarily along the Fall Line and eastern
portion of the Piedmont in the Potomac
Washington Metro and Patapsco basins.
Between now and the year 2020, the state's
population is expected to increase from
5,244,000 to 6,000,000 or about 15%. Thus,
the urban and suburban proportion of land will
likely increase to accommodate these new
Maryland residents.
About 16% of
Maryland's
land area is
urban. This
percentage is
expected to
grow to about
21% in the
next 25 years.
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Introduction
Only about 80
acres of
Maryland's
forests have
never been
logged.
Human
activity has
profoundly
aftected rivers
and streams in
all parts of the
world, to such
an extent that
it is now
extremely
difficult to
find any
stream which
has not been
in some way
altered, and
probably quite
impossible to
find any such
river.
— H.BMHynes
Land Use in Maryland
Urban
Agricultural
Forest and Wetland
Water
M ....... ililiiliilljiiililil ..... iiiiiililii .......... Ill ..... Mi I iiltilili ....... S ..... in
and is a mosaic of land uses.
iH'iliiii ..... lil'lli'il Wiiliil !•! ....... '» ..... ll!»*« **l uh A *i' it i»
e most urban land is concentrated in
m
tne
Bch ofthe Eastern Shore and central part of the
"Mil i IM
i, state is agricultural.
How Have Our
Streams Changed
Since European
Settlement?
To better understand the current state of
Maryland streams, we should look at how they
have changed in the past three centuries.
When European settlers first arrived in
Maryland in the early 1600s, our streams
meandered through mostly unbroken forests
and wetlands. Beavers were abundant—their
ponds provided diverse aquatic habitats. Old
trees died and fell into streams, creating a
labyrinth of logs, limbs, and roots that shel-
tered fish and other aquatic animals. Rain
soaked into the sponge-like forest floor,
slowly replenishing streams with fresh
groundwater during dry periods.
As the early settlers dispersed throughout
Maryland after Lord Calvert's first visit in
1634, trees were cut to provide fuel and to
make way for farm fields and settlements.
Beavers were eliminated while trying to meet
an insatiable demand for fur. To convert
wetlands to farms, streams were straightened
and cleared of wood for better drainage. Over
time, forests along streams were largely
eliminated to maximize the ability of the land
to produce crops for the settlers and their farm
animals, and also for export back to Europe.
With the trees gone and replaced by tilled and
grazed agricultural lands, soil was washed
from the land and the streams became warmer,
muddier, and more vulnerable to erosion.
Nutrients, once retained by the unhurried flow
through wetlands and. percolated through the
spongy forest floor, were quickly routed to
Chesapeake Bay. Eventually, agriculture
became a dominant feature of Maryland
landscape and remains important today. Thus,
these settlers had a much greater impact on
Maryland streams than did the Native Ameri-
cans who first occupied the land.
As towns became cities during and following
the Industrial Revolution, many streams
became open sewers or were straightened and
routed through barren concrete channels to
quickly remove storm water from the nearby
developed land and minimize flooding. No
longer could rain soak slowly into the ground.
During storms, it quickly ran off parking lots,
8
-------
Introduction
roads, rooftops, and other impervious surfaces
carrying with it a load of pollutants. Indeed,
streams were viewed primarily as a means to
convey wastes and stormwater to some "out of
sight" downstream place.
Wilson Mill on Deer Creek.
Photo by Paul Kazyak
The Industrial Revolution also brought an
increase in pollution from the air and from
underground that continues to acidify our
streams. From as far away as the Ohio River
Valley and other Midwestern U.S. industrial
areas (and as near as our own car exhaust
pipes), acidifying chemicals are sent into the
atmosphere, only to fall back to the earth as
acid rain. In some areas, acid rain has elimi-
nated all but the hardiest aquatic life in poorly
buffered streams. Our appetite for energy to
fuel our factories and heat our homes resulted
in more coal mines, especially in Western
Maryland. Today, drainage from abandoned
mines continues to pollute many streams with
toxic acid-laden water.
In summary, there are no pristine freshwater
streams in Maryland. All have been affected
by humans in some way.
This Report
Many Marylanders want to help protect and
restore our freshwater streams. To do this, we
need to work together. Individual citizens,
watershed organizations, businesses, and
local, state, and federal agencies all have a
role to play. But to help our streams, we must
have a benchmark for how healthy they are
now. We must learn what aspects of our
streams are healthy or unhealthy and work to
understand what is causing the problems, so
we can improve stream health across the state.
The purpose of this report is to describe the
health of, and impacts to, Maryland's freshwa-
ter non-tidal streams using information from
the Maryland Biological Stream Survey, or the
Survey, conducted by Maryland Department of
Natural Resources from 1995 to 1997. Al-
though the report paints a picture of overall
stream health throughout the state and by river
basin, many readers may wish to use it as a
guide for information on streams in their own
back yard or to learn how they can help
improve the quality of our streams for them-
selves, for their children, and for their
children's children. With a better understand-
ing of Maryland streams, we all can learn from
our past mistakes and become more effective
stewards of these wonderful ecosystems.
Impervious
surfaces include
parking lots,
rooftops, roads,
and sidewalks.
They prevent
rain and melting
snow from
soaking into the
ground, thus
increasing
stream flows
during storms
and reducing
stream flows
during dry
periods.
3
-------
-------
When asked the question, "How
healthy is this stream?" many of
us first think of drinking its water.
If the water is safe to drink, we may say, then
the stream is healthy. For many years, stream
protection and restoration efforts focused only
on water chemistry, without much consider-
ation of other ecosystem components. But
there's much more to the story. Although
water quality certainly is an important part of
overall stream health, we must also consider
the quality of the physical habitat—the
structure that forms the home for the stream's
inhabitants—and the inhabitants themselves.
What is the stream's biological integrity 1 Are
biological communities balanced? Are they
free to move upstream and downstream? Is
there an adequate food supply and breeding
habitat? Are they stressed, and if so what are
the stressors? A stream's inhabitants (collec-
tively called biota) are often the best indica-
tors of overall stream health.
Traditional biological stream surveys typically
focus on the residents of most concern to the
public—gamefish such as bass and trout—and
overlook most other biota. These surveys are
also conducted primarily in larger streams and
rivers that are likely to support gamefish.
Since small streams were largely ignored,
information on statewide stream conditions in
Maryland has not been available until recently.
It is these small streams that make up the
Traditional stream surveys focus on water
quality alone. The best way to assess overall
stream health is to combine water quality
with physical habitat and biological integrity.
majority of our flowing waters. Based on
1:250,000 scale maps, almost two-thirds
(66%; 5,863 miles) of all non-tidal stream
miles in Maryland are first order (Figures 4
and 5). It is these small streams, many of
which are small enough to jump across, that
often have the most intimate connection with
our backyards, streets, parking lots, and farm
fields. Second and third-order streams make
11
-------
The State of Maryland's Freshwater Streams
WHAT is A
WATERSHED?
I;
A watershed
Is an area of
land which
drains water
(and everything
the water
carries) to a
common outlet
The critical
thing to
remember
about
watersheds is
that the
streams and
rivers, the hills,
and the bottom
lands are all
part of an
inter-connected
system. Every
activity on the
land, in the
water or even
in the air,
has the
potential to
affect a
watershed.
12
up about 17% (1,500 miles) and 8% (690
miles) of all non-tidal stream miles respec-
tively. Fourth order and larger streams com-
prise less than one-tenth (9%; 788 miles) of all
stream miles statewide.
In this chapter, we provide a snapshot of the
health of Maryland's streams by describing
water quality, physical habitat, and the condi-
tion of aquatic biota for first through third-
order streams. We also examine some of the
major stressors affecting stream health result-
ing from human activities. From this informa-
tion, we hope to create benchmarks of current
status against which we can compare stream
health in the future, enabling us to document
trends and evaluate the effectiveness of our
stream protection and restoration efforts.
Patapsco River Basin
Herring Run
Watershed
Figure 4. River basins, watersheds, and stream order. One watershed within the Patapsco
t River basin is that of Herring Run. The numbers beside the streams indicate each stream's
I older- The smallest permanently flowing stream is termed first order, and the union of two
s first order streams creates a second order stream. A third order stream is formed where two
order streams join.
1st Order (66%)
4th Order and
Larger (9%)
2nd Order (17%)
3rd Order (8%)
Figures. Maryland
has over 8,800 miles
of non-tidal streams.
About two-thirds of these
stream miles are 1st order
while less than one-tenth
are 4th order or larger. The
average 1st order stream is
less than 8 feet wide.
-------
I any chemical and physical proper-
ties of water are important for
healthy streams and healthy Mary-
landers. If our streams are too acidic, too
warm, or overenriched with nutrients, stream
biota may suffer or die. If we humans drink or
swim in polluted water, our health may also
suffer. Last, but not least, the future of Chesa-
peake Bay depends largely on the quality of
the water in its streams and rivers. Because
water runs downhill across the land and into
streams, human activities on the land can
easily impact the quality of small streams and
eventually Chesapeake Bay.
This section provides an overview of pollutant
sources and the quality of water in Maryland
streams based on a single visit to each stream.
This information about water quality, while
useful, underestimates the extent of problems
associated with short-term events such as
heavy rains.
Nutrients
The primary and most widespread source of
nutrients in streams is excess fertilizer from
farm fields (Figure 6) and lawns. Nitrate-
nitrogen, referred to in this report as nitrate,
may either run off the land during storms or
soak into the ground and pollute groundwater
that may take years or even decades to reach a
stream. Although nutrients in sewage may
Excess nutrients enter streams in a variety of
ways, Including runoff of fertilizers from the
land or more directly, from animal manure.
Photo by Dan Howard
impact many Maryland waterways, sewage
treatment plants are often situated on larger
rivers and usually do not affect small streams.
Nitrate is a
commonly used
measure of
nutrient
enrichment. It
is technically
referred to as
nitrate-
nitrogen.
13
-------
Water Quality
20 40 60 80
% Agricultural Land Use
100
Figure 6. Stream nitrate
concentrations are gener-
ally higher in watersheds
with more agricultural
land use. Each dot repre-
sents one Survey sampling
site.
Septic systems can be a source of nitrate in rural
areas and areas with low density development.
Other sources of nitrate in streams include
animal manure, airborne compounds in smoke-
stack emissions, and auto exhaust.
Although excess nitrate in small streams may
produce an overabundance of algae and other
plants, the most devastating effect is in tidal
embayments and Chesapeake Bay. Here, in
combination with other nutrients such as
phosphorus, nitrate may contribute to
eutrophication.
Statewide, about 57% of all non-tidal stream
miles have unnaturally elevated nitrate levels
(greater than 1 mg/L) and about 2% have
nitrate levels greater than 10 mg/L (Figure 7).
Nitrate levels greater than 10 mg/L are above
the human health standard for drinking water
and are considered unsafe for human con-
sumption. These streams are in the Nanticoke/
Wicomico, Chester, Middle Potomac, and
Choptank River basins.
Nitrate
Concentration
< 1 mg/L [~] 1-10 mgfl ||| > 10 mg/L
Lower Potomac
Youghiogheny-- -
North Branch Potomac
Upper Potomac - -
West Chesapeake
Patuxent-
.9 EIk
Jg Pocomoke
CQ Chester- -
j* Bush-4-
t> Potomac Wash. Metro
pjj| Choptank
Middle Potomac—
Patapsco- -
Nanticoke/Wicomico -+-
Susquehanna
Gunpowder
Statewide
50
% Stream Miles
,i|j,; , ,'| '',*|l|,i , ' ;<„,;. II ij'!1 ',•.!• .;..« ,.,!' • '•: , -I I' ,„•'' .,' ',' '!'!,; "' , " ,' ,,;'llf||l \\^\ jli^lii' , •' Jl ;|'' , •• , ;,-ll'l,, | Mil1" \'ff ', '111 '|lKF' " W'flr jl IV !,i,H,f'! |l: l|'!,M.|l|iilN!llllEi !»•
iFjgure7. Streams with nitrate concentration greater than 1 mg/L are considered unnaturally
gj_-^j^^| streams with Imiu^aThuman influences. Concentrations" greater than 10 mg/L"
Sllie'S lEe ntimliuTh'eaitE1 standard for sale'''drinBng water.
iiiimn "a nl f | !!£!,i2iJl''I, I" <„„!"lhiiiiiiil;|j!| 1 imiil;;, ,'" „„' i „» 'uii
-------
Water Quality
Acidity
Acid enters streams from four main sources:
acid rain, abandoned coal mines, fertilizers, and
from decomposing leaves and other natural
organic material. Stream acidity is measured as
pH. The lower the pH, the more acidic the
stream. A pH less than 5 is considered harmful
to most stream biota, especially fish. When the
pH of stream water is too low, gill function, egg
development and larval survival are affected.
Also, the concentration of metals such as
aluminum become toxic to fish when runoff and
stream water become acidified.
Excluding streams with substantial natural
acidity, streams with pH below 5 have no fish
while streams with pH above 6 have, on
average, over 9,000 fish per stream mile
(Figure 8) based on results of the Survey.
Streams with pH between 5 and 6 have an
average of only 500 fish per stream mile.
The most widespread source of acidity in
Maryland streams is acid rain (Figure 9),
I
Smokestack emissions from factories and
power plants (some as far away as Indiana)
as well as car and truck exhaust contribute
to acid rain in Maryland. More than 80%
of all acid rain falling in Maryland comes
from outside the state.
Some streams in; Maryland are well-buffered
and thus less susceptible to acid rain impacts.
For example, many streams in the Middle and
Upper Potomac river basins flow through
limestone-rich soil and rocks. Their waters are
pH<5
More Acidic •*-
pH5-6
pH>6
• Less Acidic
Figure 8. Low stream
pH has a dramatic
effect on fish. Al-
though streams with
pH between 5 and 6
contain some fish,
those with pH less
than 5 have none.
impacting about one in five (18%) stream
miles, a length of freshwater streams about
equal to the distance from Baltimore to
Denver. Acid rain is formed by reactions of
rain with exhaust and smoke from burnt fossil
fuels such as gas, oil, and coal. Rain becomes
acidic when dissolved gases form various
acids, such as sulfuric and nitric acid, and fall
to earth. Rain is naturally slightly acidic (pH
between 5.3 and 5.7) because of its dissolved
carbon dioxide content and to a lesser extent
from chlorine. However, in some parts of
Maryland, rain has a pH of less than 4, a level
which is lethal to most stream biota.
naturally buffered by these alkaline materials.
Streams in other basins are less buffered and
unless the sources of acid rain are reduced,
these streams may either remain acidic or one
day become acidic.
Water that seeps into streams from abandoned
coal mines is called acid mine drainage or
AMD. These streams have a combination of
low pH and high sulfate. They also commonly
carry lethal levels of aluminum and high levels
other metals such as iron and manganese.
Since all of Maryland's coal mines (active and
inactive) are restricted to the mountainous
Unnatural
sources of
acidity are
perhaps the
most
devastating
chemical
impacts that
threaten
Maryland
stream biota.
15
-------
Water Quality
-------
Water Quality
The water of an unnamed tributary to
Georges Creek, in the North Branch
Potomac River basin, is brownish-orange
from acid mine drainage.
Photo by Scott Stranko
western part of the state, only about 3% of the
total stream miles statewide are acidified by
AMD (Figure 9). However, in the
Youghiogheny and North Branch Potomac
River basins (the two westernmost river basins
in the state), AMD has acidified about 25%
and 15% of the stream miles, respectively.
In some very slow moving streams of southern
and eastern Maryland, leaves and other
organic materials that fall into the water are
not flushed away by the current and may stain
the water much the way tea leaves do, result-
ing in brownish or blackish water. These
sluggish streams have earned the name
"blackwater" streams. Along with the stain,
leaves also leach acids into the water and thus
naturally acidify the water, but without the
toxic levels of aluminum that occur in streams
that are affected by acid rain and AMD.
Only about 3% of the non-tidal stream miles
in Maryland are naturally acidic (Figure 9).
Most are in the Chester, Choptank, Nanticoke/
Wicomico, and Pocomoke river basins of the
Coastal Plain. Historically, there were many
more blackwater streams throughout this
region, but with channelization and the
extensive application of lime on farm fields
for the past 100 years, the acidity of many
blackwater streams is likely less today than it
was historically. The biota of blackwater
streams are adapted to naturally acidic condi-
tions. They may actually be threatened by the
higher pH resulting from increased buffering
when farm fields are limed.
Fertilizers applied to farm fields, lawns, golf
courses, and other cultivated lands that contain
large amounts of nitrogen may also increase
stream water acidity. About 4% of Maryland's
stream miles are acidic primarily due to fertiliz-
ers. Most of these streams are on the Coastal
Plain in the Choptank, Nanticoke/Wicomico,
and Pocomoke river basins (Figure 9).
Zekiah Swamp Run, a blackwater swamp
in the lower Potomac River Basin.
Photo by Scott Stranko
In addition to
ditching and
liming, the
eradication of
beavers from
much of
Maryland's
Eastern Shore
has reduced
the number of
blackwater
streams. No
longer held
back by beaver
dams and
sinuous path-
ways, swifter
stream flows
now flush away
the leaves that
once turned the
water dark
brown to
nearly black.
17
-------
Water Quality
Maryland
has a dissolved
oxygen
criterion of
5 mg/L for
the protection
of aquatic life.
Dissolved Oxygen
Just as sufficient oxygen is necessary for
human survival, it is also critical for the
survival of aquatic animals. In most swiftly
flowing streams with riffles, there is plenty of
dissolved oxygen (DO) to support aquatic
animals because the water is aerated as it
flows and bubbles over rocks. However, in some
sluggish, low gradient streams on the Coastal
Plain, DO may drop below the state surface
water criterion of 5 mg/L (or parts per million).
When DO is low, only those organisms adapted
to low DO levels can live. Although DO may be
naturally low in many of these slow-flowing
streams, nutrients in fertilizers, runoff from
urban lands, and untreated sewage can act as
pollutants when they trigger a series of changes
that lower stream DO levels.
Statewide, 6% of all stream miles have DO levels
less than 5 mg/L. But more than 25% of the
stream miles in the Chester, Lower Potomac, and
Pocomoke river basins have DO levels below
this criterion (Figure 10). Seven river basins
contained no stream miles with low DO. Be-
cause DO varies by time of day and season, the
single DO sample per site taken by the Survey
during the day underestimates the extent of the
low DO problem in Maryland streams.
Water Temperature
Water temperature affects the health of
streams in many ways. Feeding, reproduction,
metabolism, and the abundance of aquatic
biota may all be altered by water that is too
warm or even too cold. Streams that become
too warm usually contain only organisms able
to tolerate the stresses of heat. Stream tem-
peratures also affect the solubility of com-
pounds and rate of downstream nutrient flow
to Chesapeake Bay.
Runoff of heated water from impervious
surfaces (such as streets, parking lots, and
rooftops) is a serious and widespread problem
in Maryland streams. During summer, rain that
runs off of hot impervious surfaces and flows
directly into streams causes temperatures to
rise abruptly during storms. Even during dry
periods, water temperature is usually more
variable in streams draining urban lands than
those draining farms and forests. Reasons for
this increased variability include a reduced
supply of cool groundwater and less shade
than in forested streams. Constructed ponds
and lakes, especially those located directly on
streams, also affect stream temperature
because they are sources of heated water in
summer and near-freezing water in winter.
Middle Potomac
Susquehanna
Bush
Gunpowder
Elk
North Branch Potomac
.3 Potomac Wash. Metro
£§ Patuxent
PQ Youghiogheny
Patapsco
Upper Potomac
Choptank
Nanticoke/Wicomico
West Chesapeake
Pocomoke
Lower Potomac
Chester
Statewide
n
3
% Stream Miles With DO Less Than 5 mg/L
Figure 10. Percent of stream miles with less than the state water quality criterion of 5 mg/L of
dissolved oxygen. Most impaired streams are in the heavily-farmed Chester and Pocomoke
18
-------
Water Quality
Midway Run
Land Use
Dorsey Run
Land Use
Agriculture
(31%)
Forest (73%)
Urban (37%)
Forest (32%)
Urban (10%)
Agriculture
(17%)
I
15
Midway Run
Dorsey Run
15
During 1997, water temperature was continu-
ously monitored during summer at about 200
Survey sites in 5 river basins. Although state-
wide information on stream temperature is
currently not available from the Survey, two
streams sampled in 1997 in the Patuxent River
basin—Dorsey Run and Midway Run—provide
some insight into water temperature differences
in streams with different upstream land uses.
Both are second-order Coastal Plain streams
with similar widths and depths at the sampling
sites, but different upstream land uses. Dorsey
Run's watershed is mostly forested (73%), with
only 10% urban land use. The remainder of its
watershed (17%) is agricultural. Midway Run's
watershed, however, is fairly evenly split among
i Figure 11. Water temperatures are usually lower and more stable in streams draining forested
land compared to those draining urban land.
forest (32%), urban (37%), and agricultural
(31%) land use.
In July, the water in Midway Run became
warmer in the daytime (and cooler at night)
than that in Dorsey Run (Figure 11). Also, the
highest daytime temperatures were reached
more quickly in Midway Run relative to
Dorsey Run. Had an afternoon thunderstorm
occurred during ;the period, the differences
would have been even more pronounced. The
comparison between these two watersheds
gives us insight into how the loss of natural
land cover (forest), increase in the amount of
upstream impervious cover, increase in runoff
temperature, and reduced base/low adversely
affect water quality and aquatic biota.
Maryland
water
temperature
criteria for
natural and
stocked trout
streams are
68° F (20° C)
and 75° F
(24° C),
respectively.
19
-------
-------
In addition to clean water, physical habitat
is critical for healthy streams. In general,
good stream habitats have: 1) wide,
naturally vegetated riparian buffers, 2)
meandering channels with stable, naturally
vegetated banks, 3) a variety of substrate
types (such as wood, roots, and rocks), and 4)
a variety of water depths and water velocities.
Unfortunately, humans have altered natural
stream habitats throughout Maryland, affect-
ing both water quality and aquatic life.
Riparian Zone
FUNCTIONS OF VEGETATED
RIPARIAN BUFFERS
I) Reduce dramatic fluctuations in stream
p temperature
Reduce nutrient and sediment runoff
|) Stabilize stream banks
|) Provide organic matter for stream food
1 webs
5) Provide migration corridors and nesting j
. areas for many terrestrial species
I) Supply wood and roots for channel
fV formation and habitat
I
The riparian zone is the area along the bank of
a stream, river, or other water body. Vegetated
riparian zones may act as a buffer against
pollution and are therefore very important in
mitigating the adverse impacts of human
activities. Although there are several buffer
types, forested riparian buffers provide the
best stream protection. Streamside forests
provide shade, helping to keep streams cool
and dampening fluctuations in stream tem-
perature. They provide structures such as
wood and roots that improve habitat and
stabilize channels. Like other vegetated
buffers, Streamside forests also reduce nutrient
and sediment runoff, stabilize stream banks,
and provide organic matter that can be used by
aquatic animals; Wide forested riparian
buffers protect streams from runoff and
generally provide better habitat for plants and
animals than narrow buffers. Protecting and
restoring forested riparian buffers on small
streams is critical since small streams receive
most of their flow from runoff and groundwa-
ter while larger streams receive most of their
flow from upstream tributaries that may be
poorly buffered.
Statewide, about 59% of all stream miles have
forested riparian buffers (Figure 12). About
40% of the forested stream miles statewide
have buffers greater than 50 meters (164 feet)
wide (Figure 13). Almost 60% of the stream
miles in the Lower Potomac, North Branch
WHAT IS
HABITAT?
The theater in
which the
ecological play
takes place; it
is a template for |
the biota, their
interactions,
and their
evolution.
About 25% of
all stream miles
in Maryland
lack a vegetated |
riparian zone
and thus are
unbuffered
against
stormwater
runoff.
BHB
21
-------
Physical Habitat
Twenty-seven
percent of all
stream miles
in Maryland
have no
vegetated
riparian
buffer.
The duff on streamside forest floors and the
soil beneath it act as a sponge, slowing
runoff of nutrients, sediment, and toxic
compounds into streams.
Photo by Ken Yetman
No Buffer (27%)
Forest (59%)
Other
Vegetation
(14%)
% figure 12. More than half of all stream
I miles in Maryland have forested riparian
^•Vii»w w-j"*":!i,raBHKfr,•{„,.; ' ',,,; ; ; ' ' :<„;; 1
over one-quarter are
runoff.
Potomac, Upper Potomac, and West Chesa-
peake basins have wide forested buffers. In
contrast, the Middle Potomac, Pocomoke, and
Patapsco basins each have fewer than one-
quarter of all stream miles bordered by wide
forested buffers. More than one-quarter (27%)
of all stream miles in the state are unbuffered
and 14% are buffered by vegetation other than
forest, such as abandoned cropland or lawns.
Wood in Streams
Another widespread impact to stream physical
habitat quality in Maryland is the loss or
removal of wood, such as logs, limbs, and
roots, along stream banks and in stream
channels. Destruction of riparian forests,
stream channelization, and the removal of
fallen trees from streams all contribute to this
Vegetated Riparian
Buffer Width
50 meters
and over
D
6-49 meters
0-5 meters
I
fi
Lower Potomac
North Branch Potomac
Upper Potomac |
West Chesapeake
Patuxent
Youghioghenyj^
Gunpowder!
Chester?
Potomac Wash. Metro [
Nanticoke/Wicomico \
Bush
Susquehanna
Elk,
Choptank"
Middle Potomac
Pocomoke
Patapsco,
Statewide!"
0
50
% Stream Miles
100
13. Forty'"percent of Maryland's stream miles are adequately buffered (green shading)
: Jjy'riparian vegetation (trees, shrubs, grass), 25% areonly moderately buffered (yellow
*t shading), and 35% have either narrow buffers or none at all (red shading).
22
-------
Physical Habitat
Wood in streams enhances habitat quality
in many ways.
Photo by Brian Stranko
degradation. In many streams, particularly in
the Coastal Plain, wood provides a diverse
array of stable habitats and cover for stream
animals. Limbs and roots also trap leaves, a
vital food supply for many benthic
macroinvertebrates. Undisturbed streams in
naturally-forested areas generally contain a
great deal of wood. Without these natural
structures, banks may become unstable and
erode, contributing to sediment and nutrient
pollution in downstream rivers and the Chesa-
peake Bay.
During the Survey, sampling crews noted the
number of logs, large tree limbs, and tree roots
at each sample site. Among all river basins in
Maryland, counts of wood per stream mile
range from 40 in the Upper Potomac to 220 in
the Chester basin. The statewide average is 91
(Figure 14). Coastal Plain streams, such as
those in the Chester and Choptank basins, tend
to have more wood than streams outside the
Coastal Plain, although these numbers are
likely much lower than they were historically.
Higher velocities in the steeper gradient
streams outside the Coastal Plain may flush
wood from the channel more quickly than in
the more sluggish streams of the Coastal Plain.
Channelization
As much of Maryland changed from forested
to developed land, many streams were
channelized to drain farm fields or allow for
efficient movement ofstormwater from urban
lands. In many areas of the state, channel-
ization causes the most severe physical habitat
impacts to streams. During channelization,
naturally meandering streams are straightened,
Chester
Choptank _
Nanticoke/Wicomico
West Chesapeake _,
Lower Potomac _
— Pocomoke _
•g Patuxent _
« BuSh-
ClS Pllr
|j Gunpowder _
.5* Patapsco _
(5{ Susquehanna -
Youghiogheny _
Middle Potomac -
Potomac Wash. Metro _
North Branch Potomac -
Upper Potomac -
1 btatewuie ~|
x-i • —
5fes--~ - <-•-„'•. * •' * r ',-.'•' - !p'"rT •. '-.T-,--, f..jv- «-J"~- ,/vf-r ..." -^- Zjf*
tm^^^^^^^^^^K^j?-
£- iii, .X"
0 50 100 150 200 250
Amount of Wood per Stream Mile
I Figure 14. Coastal Plain streams tend to have more wood, roots, and limbs than those outside
f the Coastal Plain. These structures provide valuable habitat for stream animals
f~. . -.- •' • -...-.- • • -•••:.--. .,'. . '. ,-, •!-...•:, ...•,;'.:_ >••;,; :. ••......•-/ H
WOOD IS
GOOD
In streams that
drain farm
fields, large
limbs and tree
trunks are
often removed
to keep the
water flowing.
This practice
generally
decreases
habitat quality
for fish and
aquatic
invertebrates.
23
-------
Physical Habitat
Stream
channelization
is more
prevalent in
agricultural
areas
containing
wetlands.
Stream channelization comes in many
forms. Along farmland (above) many
streams are stripped of their riparian
vegetation and straightened. In urban areas
(right), they are often lined with concrete.
Photos by Niles Primrose (above) and Dan
Howard (right)
riparian vegetation is often cut, and wood is
removed from the stream. Fortunately, many
streams in agricultural areas that were
channelized a century or more ago are now
beginning to revert to a more natural state.
This may be reflected in the higher amounts of
wood in streams of the Coastal Plain, de-
scribed above. The most extreme habitat
impacts come in urban areas when streams are
converted to concrete-lined ditches that
provide minimal habitat for only the hardiest
aquatic biota. With straightened channels and
less obstructed flows, channelization also
increases the speed at which nutrients and
sediment flush from upland streams to down-
stream rivers and Chesapeake Bay.
About 17% of all stream miles statewide are
channelized (Figure 15). More than one-half
of the stream miles are channelized in two
3
West Chesapeake
Bush
Youghiogheny
Patuxent
Lower Potomac
Susquehanna
Gunpowder
Middle Potomac
North Branch Potomac
Elk
Upper Potomac
Patapsco
Potomac Wash. Metro
Choptank
Chester
Nanticoke/Wicomico
Pocomoke
Statewide
50
% Stream Miles
100
is! 'Stream cliannelizafion "m MarylancTis more p^vaTBnTm''ffi¥"Coastal Plain and in
the heavily urbanized central part of the state.
24
-------
Physical Habitat
heavily fanned river basins on the Eastern
Shore: the Pocomoke and Nanticoke/
Wicomico. Because both basins contain many
wetlands, which are not suitable for farming,
channelizing streams here to produce arable
land was more common than in other basins.
About one-quarter of all stream miles in the
Patapsco and Potomac Washington Metro
basins are channelized, primarily to drain the
expansive impervious areas in and near
Baltimore and the District of Columbia.
Bank Stability
Excessive stream bank erosion is one sign of
poor physical habitat with both near and far-
reaching consequences. Natural stream banks
are stabilized with tree roots, logs, rocks or
other materials that minimize erosion even
during floods. Soil from eroding banks be-
comes sediment that is moved by the current
and coats the stream bottom, reducing available
habitat for benthic macroinvertebrates and
spawning areas for fish. Excess sediment in the
stream channel also causes bank erosion farther
downstream. This same sediment clouds the
water, smothers aquatic plants, clogs the gills of
aquatic animals, and carries nutrients contribut-
ing to eutrophication in Chesapeake Bay.
Thirty percent of all stream miles statewide
have good bank stability (Figure 16). More
than two-thirds of the stream miles in the two
westernmost basins, the North Branch
Potomac and Youghiogheny, have good bank
stability. In contrast, almost three quarters
(75%) of all stream miles in both the Gunpow-
der and Patuxent basins have poor bank
conditions. Streambanks in Western Maryland
may be naturally more stable than those to the
east because rocks (boulders and bedrock) are
more prevalent in and along stream channels
About one-half
of all stream
miles in
Maryland
have unstable
stream banks.
Bank erosion is often most severe where
there is little vegetated riparian buffer and
few roots to hold the soil.
Photo by Dan Boward
I
3
North Branch Potomac
Youghiogheny
Potomac Wash. Metro
Upper Potomac
Choptank
West Chesapeake
Elk
Pocomoke
Middle Potomac
Susquehanna
Chester
Patapsco
Bush
Nanticoke/Wicomico
Lower Potomac
Patuxent
Gunpowder
Statewide
25
50
% Stream Miles
75
100
•Figure 16. Streams in the western part of Maryland tend to have more stable banks than
vthpse in Jhe easj;, Erosion from unstable banks contributes to downstream sedimentation
problems m larger rivers and Chesapeake Bay.
25
-------
Physical Habitat
The Physical
Habitat Index
incorporates
several
measures of
habitat quality
into one easily
understood
number
in the west, and thus provide more stability for
stream banks. But in urban areas, such as
portions of the Patuxent and Gunpowder
basins, stream channelization and elevated
flows during storms may dramatically increase
bank erosion, especially where banks are not
well armored by stable structures such as
wood and rocks.
Overall Physical
Habitat Quality
Although we may gain insight into specific
physical habitat problems by examining one
habitat measure at a time, it is useful to
combine these measures (e.g., riffle/run
DNR recently developed a provisional
' I 11111 III III 1 1 . . . Y 1.-.L X '
index to evaluate physical habitat
1 ............... c'oWitions" InTSoBidal
_
streams. By comparing various physical
' "',n 'characteristics of' one stream to the _ ^
characteristics of least impaired streams,"
the Physical Habitat Index (PHI)
generates a score that rates the overall
.............. ' ........ physical haEita! ..... qualify of the sampled
stream segment.
quality and instream habitat) to assess the
overall physical habitat condition of a stream.
Based on the provisional Physical Habitat
Index (PHI) developed for the Survey, about
20% of all stream miles in the state are in
good condition, while 52% are poor (Figure
17). More than three-quarters of all stream
miles in the West Chesapeake and Nanticoke/
Wicomico basins are in poor condition, hi
contrast, the Elk and Susquehanna basins had
the lowest percentages (11% and 25%, respec-
tively) of stream miles rated poor for physical
habitat quality.
Although the PHI scores should be considered
preliminary, our results suggest that physical
habitat degradation is an important, widespread
problem in Maryland streams. Because riparian
buffer zones are such an important attribute of
streams and rivers, riparian forests should be
staunchly protected. Replanting protective
vegetation along streams with adequate riparian
buffers is an obvious starling point in the
restoration process that should eventually
increase PHI scores. Long-term stream moni-
toring programs should accompany all restora-
tion efforts to evaluate their success.
Overall Physical
Habitat Quality
Good
1
«
1
Elk
Choptank
Bush
Gunpowder
Patapsco
Lower Potomac
Susquehanna
Middle Potomac
Patuxent
Youghiogheny
West Chesapeake
Upper Potomac
North Branch Potomac
Potomac Wash. Metro
Nanticoke/Wicomico
Chester
Pocomoke
Statewide
50
% Stream Miles
"the 'Physical
j figure 17. Statewide, about one-fifth of the stream i
i:: ^" "'""tat |nSex wHile a liffiepverhatf are"rate^d poor. The Elk River basin contains the
e|t -»g2** oTstream SSfes rateSTgood^y this lno'e£ 'More 'than" one-half the stream
miles are rated poof "inIT of the 17 basins.
26
-------
Reptiles and
Amphibians
Amphibians and reptiles (collectively called
herpetofauna, or herps) are excellent indica-
tors of stream and watershed health. Because
many of these animals live part of their lives
in water and part on land, their survival
depends not only on water quality but also on
the physical make-up of both environments.
Forty-five species of herps were found
statewide during the Survey, and 9 out of 10
stream miles harbor at least one species. Of
these 45 species, 29 are either aquatic or
intimately dependent upon riparian environ-
ments. In general, fewer herp species live in
or near Coastal Plain streams than elsewhere
in the state. The number of species per basin
ranges from 28 in the Patuxent River basin to
10 in the Nanticoke/Wicomico and Bush
basins (Figure 18).
Although several herp species are sensitive to
acid rain and other water quality impacts,
results from the Survey suggest that, in
Maryland, urbanization has a larger impact on
herp species diversity, with fewer species
occurring in more urbanized areas. Only seven
of the 29 aquatic or riparian species were
found at sites where watershed impervious-
ness exceeded 25%, while 22 species occurred
Black Rat Snake
Photo by Paul Kazyak
at less urbanized sites (Figure 19). Four
species of salamanders occurred exclusively at
sites within the least urbanized watersheds
(<3% impervious land cover).
The amount of
urban land in
a watershed
influences which
reptiles and
amphibians
can live in its
streams. A
number of
species can not
tolerate the
sometimes
harsh
conditions
found in urban
streams.
27
-------
Aquatic Life
Mountain
dusky, seal,
Jefferson, and
northern slimy
Salamanders
were never
found in
urbanized
watersheds
with more
than 3%
impervious
land cover.
Frogs and toads
I Salamanders
inn Turtles, Snakes, and
lizards
.a
2
Patuxent -"
Upper Potomac
Lower Potomac
North Branch Potomac
Middle Potomac
Youghiogheny
Potomac Wash. Metro
Patapsco
Susquehanna
West Chesapeake
Choptank
Chester
Gunpowder
Pocomoke
Elk
Bush
Nantkoke/Wicomico -
Statewide -
0
10 20 30 40
Number of Herpetofauna Species
Figure I'll Forty-five "species oFherpetbfauna were found during the Survey. No salamanders
i were found in the"Chester, Pocoinoiffi, or Nanticoke/Wicornico river basins.
MOUNTAIN DUSKY SALAMANDER
SEAL SALAMANDER
JEFFERSON SALAMANDER
MORTHERH SUMY SALAMANDER
AMERICAN TOAD
BUCK RAT SNAKE
COMMON HUSK TURTLE
EASTERH MUD SALAMANDER
FOJYLER'STOAO
LONGTAR SALAMANDER
NORTHERN LEOPARD FROG
NORTHERN DUSKY SALAMANDER
NORTHERN CRICKET FROG
NORTHERN RINGNECK SHAKE
NORTHERN SPRING SALAMANDER
PlCKEKEt FROG
RED SALAMANDER
RED SPOTTED NEWT
SOUTHERN LEOPARD FROG
SPOTTED TURTLE
WOOD TURTLE
WOOD FROG
BULLFROG
COMMON SNAPPING TURTLE
NORTHERN WATER SHAKE
6REEN FROG
NORTHERN TWO-LINED SALAMANDER
EASTERN BOX TURTLE
REDBACK SALAMANDER
3-25%
IMPERVIOUS SURFACE
ESS THAN 3%
OUS SURFACE
=3 :: '
: Figure 19. Of the 29 aquatic or riparian species of herpetofauna found during the Survey, only
» 7 occurred in heavily-urbanized areas (>25% impervious land cover in the upstream water-
§hed). Cqnversely, 4 species of salamanders (in blue) never occurred in urbanized areas (>3%
,:,, jmperVious land cover).
-------
Aquatic Life
Fish
General Description
Maryland's streams are home to a diverse
array of native fishes that are often unnoticed
by most stream observers. Numbering more
than 100 species, the total population of
Maryland stream fish exceeds 61 million.
From tiny and reclusive shiners to big and
brash catfish, these animals are key compo-
nents of balanced stream ecosystems. Because
many fish consume benthic macroinverte-
brates, aquatic plants, or detritus, and are
themselves eaten by larger fish, they provide
an integral link in stream food chains.
Maryland's stream fish are exposed to many
physical and chemical stressors, including
stream channelization, dams, toxic contami-
nants, introduced species, and acid rain.
Because they often show a range of tolerance
to stream degradation, fish communities are
good indicators of overall stream health.
These communities include many species that
are unfamiliar to most of us, but are nonethe-
less a vital part of our stream ecosystems. The
Survey provides us with both basic informa-
tion on fish communities in our streams (that
can serve as a baseline for future assessments)
and a way to examine how stressors affect
both fish communities and individual fish
species.
Creek chub (6%)
Rosyside dace (5%) Other species (41 %)
Tesselated darter (4%)
Eastern
mudminnow
Blacknose dace
Mottled sculpin (19%)
(13%)
tFigure 20. Of the approximately 61
^million fish in Maryland's streams, the
|pollution-tolerant blacknose dace is the
! most abundant.
Rosyside dace
Photo by Brian Stranko
The most abundant (19%) fish in Maryland's
streams is the pollution-tolerant blacknose dace
(Figure 20). Other common species include the
pollution-tolerant eastern mudminnow and
creek chub, moderately pollution-tolerant
mottled sculpin and tesselated darter, and
poUution-intolerant rosyside dace.
Introduced Fish
Introduced (sometimes called non-native or
exotic) fish species are a common occurrence
in Maryland's streams. As far back as the
Goldfish.
Photo by Bob Lunsford
•»m*l»B.' wJ^^:f*faai|i*^iWj^:jl,M^gt«liH&^'^^;^|
1870s, habitat destruction and overharvest
depleted native fish populations to the point
that the only viable alternative to sustaining
recreational fisheries was thought to be the
introduction of new species. In the last 125
years, many species have been stocked in an
effort to boost the variety and quality of
fishing opportunities in Maryland waters.
Some, such as the popular largemouth bass
and not-so-popular common carp, have been
There are about
12 times as
many stream-
dwelling fish
in Maryland
as there are
people. Of all
these fish,
only 3% are
gamefish—
those most
familiar to us.
29
-------
Aquatic Life
Almost one in
two stream
miles in
Maryland now
harbors at
least one
introduced
(non-native)
fish species.
highly successful in adapting to Maryland's
environment. Other non-natives have entered
Maryland streams via other, less intentional
means, such as from angler bait buckets and
release of aquarium pets.
About 20 species of introduced fish live in
Maryland's streams. Some of the species not
native to all or most of the state include:
goldfish, fathead minnow, green sunfish,
channel catfish, bluegill, brown trout, rainbow
trout, largemouth bass, and smallmouth bass.
Almost one-half (45%) of the stream miles
statewide have at least one introduced fish
(Figure 21). In general, river basins on the
Eastern Shore have more introduced fish per
stream mile than basins hi other areas of
Maryland. About three-quarters of the stream
miles in the Elk and Choptank basins have
introduced fishes, while less than one-quarter
of the stream miles in the North Branch
Potomac and Upper Potomac basins contain
them. Because most introduced fish species in
Maryland streams are adapted to life in large
streams and rivers, they are less likely to be
found in small streams (Figure 22).
Because many studies have shown that intro-
duced species can reduce or even eliminate
native species through competition and preda-
tion, proposals to introduce non-native fish in
new areas are now subject to careful review and
consideration before action is taken. This
approach should help to minimize adverse
effects on our native fauna in the future.
123
Stream Order
f Figure 22!. Throughout Maryland, intro-
fduced fish occur more than twice as often
-in 3M order streams than in 1st order
^streams.
West Chesapeake
North Branch Potomac
Upper Potomac
Youghiogheny
Bush
Lower Potomac
Patuxent
Susquehanna
Middle Potomac
Gunpowder
Patapsco
Nanticoke/Wicomico
Pocomoke
Potomac Wash. Metro
Chester
Choptank
Elk
Statewide
% Stream Miles
I Figure 21. Almost half of Maryland's stream miles have introduced fish. They are generally
, more common in Coastal Plain streams, especially on the Eastern Shore.
30
-------
Aquatic Life
A Tale of Two
Natives
Once numbering more than 3 million, only
about 300,000 brook trout now live in Mary-
land streams. Today, brook trout are found in
scattered portions of the Piedmont (Patapsco,
Gunpowder, Bush, and Lower Susquehanna
basins) and the Allegheny Plateau (North
Brook Trout
Photo by Paul Kazyak
Branch Potomac and Youghiogheny basins)
(Figure 23). No brook trout were found in the
Coastal Plain during the Survey, although they
are known to occur in Jabez Branch, a tribu-
tary to the Severn River in the West Chesa-
peake basin.
Although reasons for the decrease in brook
trout are many, one of the most important
factors may be water temperature. As trees
were cleared for agriculture and housing,
previously forested streams were exposed to
direct sunlight as well as hot water runoff from
impervious surfaces like roads and rooftops
(Figure 24) and warm water discharges from
ponds and lakes. Today, fewer and fewer
streams are cool enough to support brook
trout, particularly in the eastern half of the
state. In addition to impervious surfaces, other
major threats to the continued existence of
brook trout in Maryland include silt from new
construction and agriculture, competition from
non-native brown trout, loss of forests along
streams, acid rain, acid mine drainage, and
global warming.
The story of American eel in Maryland
streams is much like that of brook trout. Since
the time of European settlement, distributions
of this species have changed in response to
impacts to their migratory routes. Early
settlers built many small dams to supply water
power for mills. Later, more dams were added
for water supply, flood control, and hydroelec-
tric projects, and additional barriers were
created during road construction. Today, there
are more than 1,000 man-made barriers to
migratory fish in Maryland (Figure 25), and
• Current Distribution
•I Historical Distribution
figure 23. Historically, brook trout ranged from the Fall Line to the western border of the state.
Kurrent distributions (Survey sites with brook trout) are limited to portions of central and
western Maryland.
Two native
Marylanders,
brook trout
and American
eel, were once
abundant and
widespread in
our streams.
Brook trout
were never
found in streams |
with greater
than 2%
impervious
land cover in
the upstream
watershed.
31
-------
Aquatic Life
DID YOU
KNOW?
American eels
may live up to
30 years. The
oldest one on
recofd was 85!
Eels do not
become
definitely male
or female until
they are about
10 inches long.
32
| 2500-
§ 2000-
£.8
M'g 1500-
la
« | 1000-
°l
« 500-
& i
•
*
f '
1 » * • •
»*. i • - i
r 1 1
} 1 2 3
% Impervious Land Cover
Figure 24. Brook trout are extremely
^sensitive to the amount of roads rooftops,
I" I II I I'Illl" ill III I'll i I I i I" I IJ I '.
and other impervious land cover in a
watershed.
access to historical spawning and nursery
habitat has been greatly reduced for many fish
species hi addition to eels.
An example of the decline of American eel
abundance resulting from dam construction
can be found in the lower Susquehanna River.
Prior to the completion of Conowingo Dam in
1928, the annual harvest of eels in the river
was nearly 1 million pounds. Since then, the
Spawning in the depths of the Atlantic
Ocean, many American eels migrate to
small freshwater streams in Maryland
where they mature and spend much of
their adult lives.
annual harvest has been zero—eels have all
but disappeared above the dam (Figure 26).
Even in areas without migration barriers,
widespread loss of habitat continues to limit
eel abundance in Maryland streams. The
results of the Survey make it clear that addi-
tional efforts will be necessary if we are to
protect the living heritage of brook trout and
American eel for future generations.
ere are more than 1,000 known blockages to fish migration, on Maryland's streams,
Including 3ams"I curvertsipipe eras'slngsTand gabions. Most documented blockages are east of
the Fall Line and prevent migratory (anadromous and catadromous) fish from migrating up-
stream from Chesapeake Bay to points west. These blockages are the initial focus of DNR's fish
passage program. Once passage has been restored at these blockages, DMR will focus its efforts
on blockages in the western part of Maryland. '
-------
Aquatic Life
• American eel present
• American eel absent
— Conowingo Dam
Figure 26. Conowingo Dam blocks the migration of American eel. During the Survey, eels
^ were found at only two sites upstream of the darn. Because they must swim through the dam's
.hydroelectric turbines to return to the sea as mature adults, eels that manage to pass through
• Conwingo dam may be injured or killed and unable to complete their life cycle.
Rare, Threatened,
and Endangered
Fish
Maryland darters are small, inconspicuous
bottom-dwelling fish, federally listed as
endangered. They were last observed in the
Deer Creek watershed (Lower
Susquehanna River basin) in 1987 and are
believed to be extinct. A restriction of their
range may have occurred with the comple-
tion of the Conowingo Dam on the
Susquehanna River in 1928. Siltation and
water withdrawl for drinking and irriga-
tion are considered to be the principal
threats to the last known population.
Photo by Jim Williams
^ The Endangered Species Act of 1973
h-classifies a species as either endangered
I when it is in danger of extinction within
I the foreseeable future, or threatened
pwhen a species is likely to become
| endangered if its numbers continue to ;
| dwindle. Maryland has several classifica-
! tions of rare species that vary according
i to a species' distribution, estimated
j number of populations, and their viability.
h .
Over the past few decades, there has been
increased concern among scientists, natural
resource managers, and the public over the loss
of native plant and animal species locally,
regionally, and world wide. Although species
extinction is a natural phenomenon, it has
increased dramatically in the last century as a
result of human activities. While newspaper
stories often tell of extinctions in far away
places such as tropical rain forests, the streams
in our own backyards contain plants and
animals that also need our attention and protec-
tion. Rapid, uncontrolled development, acid
rain, and a host of other human influences
contribute to the widespread loss of habitat
vital to stream dwellers. Concern for many of
these species is not new. Federal and state
33
-------
Aquatic Life
Table 2. Rare and endangered Maryland fish species based on the Survey and listed by
Maryland DNR^ There are about 500,000 pearl dace in Maryland. This may seem like quite
, a few compared to stripeback darter (<600). Why are pearl dace considered rare if there are
- so many? In Maryland, pearl dace are found only in streams draining to Antietam Creek and
MarslJ Run in tfiSTOppS Potomac River basin. Because this rare species literally has all its
eggs in just a few baskets, it is highly vulnerable to stream degradation.
lilllH Illiinii'lii I! I'linili! 1 iWl«UV <• I Sll? l"lii!|'"l I i" "'nl1 IT'' 'HII I11!1!!;!!'111'1!1!!1: !li'"! 'I'l'l1;1"'* llin ! Jiij!
,n,,,i,i' in uiiiininL.a.iLuMg^i: • • .'• : s_u: 1±.
Species
Rainbow darter '
Stripeback.darferi1",''
''JlWtis;
Estimated Number in Maryland
Flier5;" ^
Ironcolor shiner81
Comely shiner
Glassy darter51'15
Logperch51
Striped shiner
Johnny darter
American brook lamprey;
Mud sunfish82
Swamp darter
Warmouth
Silverjaw minnow
Shield darter
Banded sunfish
Brook trout ,.„;• .;;-'
Checkered sculpin
Pearl dace
4tHOOO
500,000
Notes on current listings
E Endangered hi Maryland
SI Extremely rare in Maryland
52 Rare hi Maryland
83 Uncommon in Maryland
su Rare-uncertain status in Maryland
Each of
these species
occur in less
than 0.5%
of Maryland's
streams
Each of
these species
occur in less
than 5% of
Maryland's
streams
34
-------
Aquatic Life
Number of Species
^. Distribution of rare and endangered fish species in Maryland. Watersheds, described
on page 51 of the Technical Appendix, are shaded by the number of species found by the Survey.
agencies may classify species as rare, threat-
ened, or endangered, and focus programs (e.g.,
protection and restoration) on them.
In Maryland, we are faced with the potential
loss of several fish species, a situation that
often goes unnoticed until it is too late. Results
of the Survey support the current state listings
of stripeback darter and glassy darter and show
that other species (e.g., flier, ironcolor shiner,
glassy darter, logperch, and mud sunfish) may
also warrant listing (Table 2). Populations of
these animals are either alarmingly low, or they
are restricted to the few areas where habitat
quality is still favorable. Unfortunately, some
species like the federally endangered Maryland
darter were not found at all by the Survey and
may be extinct.
Although state-listed rare and endangered fish
are found in several watersheds throughout
Maryland, some areas, like Zekiah swamp in
the Lower Potomac basin, Tuckahoe Creek in
the Choptank basin, and the Upper Pocomoke
River, have up to four such species in their
watersheds (Figure 27). Watersheds of the
Casselman River in the Youghiogheny basin,
Lower Monocacy River in the Middle
Potomac basin, Western Branch of the
Patuxent River, and the Lower Pocomoke
River contain up to three rare, threatened or
endangered fish species each. No federally
listed threatened or endangered fish species
were found by the Survey.
Benthic
Macroinvertebrates
Benthic macroinvertebrates, or more simply
"benthos" are animals without backbones that
are larger than a pinhead. These animals live
There over 350
types (taxa) of
benthic
macroinverte-
brates in
Maryland
streams.
Predatory hellgrammites live under large
rocks in swiftly-moving streams.
Photo courtesy of the North American
Benthological Society.
35
-------
Aquatic Life
Because
benthic
macroinverte-
brates are
found in
almost every
Maryland
stream and
are easy to
catch with
inexpensive
equipment,
several
volunteer
monitoring
groups use
them as
indicators of
stream health.
- ' ;i»''" " '* '' '•- *••"- '*r"- • • >' ••' " -1'"" •:*', i
i watershed.
iiiiiii0^^^^^^^^^ iiiA^^^^
11' ' lllllllilii;!3iilllNlilllllll!i
-------
Aquatic Life
Figure 29. In the Middle
Potomac basin, pollution-
sensitive stoneflies were
found primarily in forested
areas while pollution-tolerant
black flies were found in all
areas of the basin.
Index of Biotic
Integrity
Although we can evaluate individual aspects of
stream health, such as the presence or absence
of rare, threatened, or endangered fish species,
or the number of pollution-sensitive benthic
macroinvertebrates, it is quite useful to com-
bine several measures of stream community
health into one overall value, or index. By
using an index, complex ecological informa-
tion can be summarized and stream health can
be rated as either good, fair, or poor.
One such index of the overall health of stream
communities is the Index of Biotic Integrity,
or IBI. Benthic macroinvertebrate and fish IBIs
developed for the Survey reflect the structure
and function of these communities as com-
pared to reference (healthiest) streams within a
similar region. Streams rated good or fair by
the IBIs are considered healthy compared to
the reference streams. Good streams are
comparable to the highest quality reference
streams and fair streams are comparable to the
remainder of the reference streams. Poor
streams are considered unhealthy compared to
reference streams. These Indices have several
measures or metrics that describe, for example,
the number of species (a measure of commu-
nity structure), the feeding mode (a measure of
community function), pollution sensitivity, and
proportion of introduced species, and thus
provide us with a picture of overall ecological
stream health. The EPT Index, described in the
preceding section, is one component of the
benthic macroinvertebrate IBI. See the Techni-
cal Appendix for a more detailed explanation
of the fish and benthic IBIs.
Based on the benthic macroinvertebrate IBI,
only 11 % of all non-tidal stream miles in
Maryland are in good condition, while just
over half (51%) are in poor condition (Figure
30). This index rates the remaining stream
miles (38%) as fair. The fish IBI paints a
somewhat different picture of the health of
Maryland streams. One-fifth (20%) of all
stream miles are rated good, almost one-third
(29%) are rated poor, and 26% of the stream
miles are rated fair by the fish IBI. Because
benthic macroinvertebrates and fish have
different pollution sensitivities, habitat re-
quirements, and abilities to avoid pollution, it
is reasonable to expect that these two IBIs may
not always agree at the same stream site.
By combining the benthic and fish IBIs, we
get a more integrated picture of overall stream
health as measured by both aquatic communi-
ties. For all non-tidal stream miles in Mary-
land, the provisional Combined Biotic Index
(CBI) rates almost one-half (46%) of all
stream miles poor, 42% fair, and 12% good
(Figure 31). Using this combined Index, the
Potomac Washington Metro basin has the
smallest percentage of stream miles rated good
(<1%) while the Bush has the highest percent-
age in this category (25%).
The Index of
Biotic Integrity
provides us
with an overall
picture of
stream health
by quantifying
the condition
of fish and
benthic
macroinverte-
brate
communities.
37
-------
Aquatic Life
Fish ffil
BentMc IBI
NoIBI
(26%)
Good
(19%)
Poor
(29%)
Poor
(51%)
Fair
(26%)
Fair
(38%)
Good
(11%)
30. The health of Maryland's streams as indicated by me fish and benthic
MacTolnvertebrate Indices of Biotic Integrity (IBIs). Fewer stream miles are rated good and
more Stream miles are rated poor by the benthic IBI. Fish IBIs were riot calculated for small
streams (watershed upstream <300 acres) while benthic IBIs were not calculated for streams
* with very low subsample sizes (<60 organisms).
Urbanization is perhaps the greatest stressor to
the biota of Maryland streams. As noted in the
brook trout example on page 37, the impacts
from urbanization to stream habitats and water
quality are often so severe that even minimal
amounts cause degradation and loss of re-
sources. This fact is supported by the relation-
ship between the percent of impervious land
cover upstream of Survey sample sites and the
CBI (Figure 32). When watershed impervious-
ness exceeds 15%, stream quality was never
rated good, thus illustrating one of the natural
resource benefits of focusing growth into areas
that are already urbanized and limiting the
amount of impervious land cover throughout
the state.
The Future of
Maryland's Streams
As we look ahead to the future of Maryland
streams, it is critical to reflect on the past and
evaluate the present. Although we are moving
in the right direction in many ways, such as
controlling non-point source runoff, point
source discharges, and providing passage to
Combined Biotic
Index
Good
Bush
Upper Potomac
Choptank
Elk
Susquehanna
North Branch Potomac
Gunpowder
Youghiogheny
Chester
Lower Potomac
Patuxent
Middle Potomac
Pocomoke
Patapsco
Nanticoke/Wicomico
West Chesapeake
Potomac Wash. Metro
Statewide
50
% Stream Miles
100
Figure SLrhe provisional Combined Biotic Index (CBI) provides a picture of stream health
basedon bothbenthic and fish communities. Statewide,almost one-half of'all stream miles are in
poor condition based on this Index.
38
-------
The Future of Maryland's Streams
15-
*8 PQ
QA Q)
2 £
.•B ^>
cc *
"I 1 ^3
e o
f
gi?
L-
»'•
f •
»»••
n
ii
i '"'
i
r •
|.|
P •
'*" ~-- ^1
|y| pi
<5 5-10 10-15 15-20 20-25 25-30 >30
% Impervious Land Cover
Figure 32. The amount of
impervious land cover
upstream of a stream site
influences the Combined
Biotic Index (CBI), a biologi-
cal measure of stream health.
When watershed impervious-
ness exceeds 15%, stream
health was never rated good.
migratory fish, human activities continue to
impact Maryland streams, Chesapeake Bay,
and, although often ignored, even the Gulf of
Mexico. Fish communities are unhealthy in
Youghiogheny River Gorge
Photo courtesy ofMD DNR
more than a quarter of our stream miles, while
more than half of all stream miles have
benthic macroinvertebrate communities in
poor condition.
Beyond the community level, 7 of the 100 or so
freshwater fish species in Maryland are af-
forded special protection because they are in
danger of extinction and an additional 15
species appear to be at similar levels of risk.
When individual river basins are considered,
the number of populations that may be threat-
ened or endangered grows even larger. American
eel and brook trout, once abundant in Maryland
streams, are now restricted in number and
distribution. Clearly, there is much work ahead if
we are to save our remaining resources and
attempt to restore some of what we have lost.
More than one-third of our stream miles have
little or no vegetated riparian buffers. While
there is increasing interest in protecting and
reestablishing riparian buffers, forested areas
along streams continue to be lost, even on
public lands. Although achieving Maryland's
goal of 600 additional miles of forested stream
buffers by the year 2010 (Maryland's Stream
Releaf Program) will be a landmark achieve-
ment, much more needs to be done. We also
need to recognize the vital importance of
allowing trees that die naturally to fall into
streams, where they create more habitat in
those streams and rivers that already have
forested riparian buffers.
Conversion of farmland and forest into urban
areas continues at a rapid pace in Maryland.
At the current rate of population growth and
development, an area the size of Baltimore
County (612 square miles or about 5% of
Maryland's total area) will be urbanized in the
next 25 years. The old adage that "an ounce of
prevention is worth a pound of cure" is
especially appropriate when considering the
effects of urbanization—we now know that
living resources in streams are impacted even
at low levels of urbanization and that these
impacts become pronounced when the amount
of impervious land cover exceeds 15% of a
watershed. Another problem is population
growth. With the projected rate of population
increase in Maryland, many streams in the
state will become more degraded by the
cumulative impacts of too many people.
The future health of many Maryland streams
will be dependent on our commitment to
redirect population growth and development
into existing urban areas rather than continue
to "sprawl" into forested and agricultural
areas. Streams that are currently healthy
should be protected—the most cost-effective
Water is the
most critical
resource issue
of our lifetime
and our
children's
lifetime. The
health of our
waters is the
principal
measure of
how we live
on the land.
— Luna Leopold
39
-------
It Will Take Teamwork
There are
many ways
we can all
help keep
our streams
healthy:
• don't over-
fertilize
lawns
• stop septic
system
seepage
• plant trees,
shrubs, and
ground cove
to reduce
runoff
40
strategy. But, for those streams that have been
degraded by urbanization, intense agricultural
practices, acid mine drainage, or acid rain,
some level of restoration may be needed.
Restoration includes a broad range of manage-
ment actions designed to help streams recover
and function at a self-sustaining level. The
first and most important step in a restoration
action is to halt, wherever possible, the
disturbance that is causing degradation.
Restoration actions can range from inexpen-
sive, passive approaches that involve little
more than removal of the disturbances so
natural recovery can occur, to much more
costly and active restoration measures where
the stream cannot recover naturally. Urban
stream restoration projects can effectively
improve portions of badly degraded streams.
However, where substantial intervention is
needed, these efforts can be costly (as much as
$1 million per mile of stream).
Today, many of the opportunities for stream
restoration are also found in agricultural areas.
Based on our experience during the Survey,
farmers in Maryland have expressed a general
willingness to modify the way they farm. For
example, many are willing to use Best Manage-
ment Practices, such as no-till fanning and
contour plowing, to better protect and restore
aquatic resources, but not at the expense of their
livelihoods. A clear challenge for the future will
be to protect and restore farmland streams
without jeopardizing our farming heritage.
Replanting riparian buffers is one of many
ways we can work together to restore our
streams.
Photo courtesy ofMD DNR
In addition to impacts from land development,
our growing and seemingly insatiable demand
for energy is a current and future problem for
Maryland streams. As Marylanders continue
their exodus from existing urban areas and move
into larger homes that are farther from their
workplaces, fuel consumption and the number of
vehicle miles traveled in Maryland increases
annually, and the amount of nitrogen and acids
added to streams from the atmosphere continues
to be a major problem. New regulations for air
and water quality management have helped to
reduce some types of impacts, but significant
problems remain. For example, almost one-fifth
of Maryland's stream miles are affected by acid
rain, and with expected increases in population
and vehicle miles, the amount of nitrogen that
ends up in streams and the Chesapeake Bay is
expected to increase each year.
In spite of all the problems with Maryland's
streams, their future is bright in many respects.
We have many opportunities to protect our
healthy streams, improve those that are un-
healthy, and change our lifestyles to reduce our
"footprint" on our streams. Results of the Survey
provide valuable information for tracking these
improvements, but we'll need to work together
to make it happen.
It Will Take
Teamwork
We Marylanders need to work together to
protect and restore the health of our streams.
If we are to do this effectively, we need to
acknowledge the extent of the problem and
educate others. Then, we need to make a
sustained commitment to change our present
behavior and correct the mistakes of the past.
Our children, grandchildren, and their
grandchildren are all depending on us to do
the right thing.
Results of the Survey have helped demonstrate
that there are no longer any pristine streams in
Maryland. A disturbing number of streams are
unhealthy, and rarely is there a single cause of
the degradation we observed. However, in
spite of water quality and habitat problems
revealed by the Survey, many healthy streams
still exist and protection of these streams
should be a top priority.
-------
It will Take Teamwork
Stream restoration project in Sawmill Creek; Patapsco River basin (during channel recon-
struction in 1994 and after in 1997). This project involved the cooperation of many state
and local agencies as well as concerned citizens. Since completion of the project, the once
badly eroding stream channel has been stabilized and aquatic life is recovering.
Photos by Larry Lubbers
Stream restoration will not be easy. However,
challenges create opportunities. The challenge
of protecting and restoring streams for future
generations of Marylanders should be consid-
ered as a wealth of opportunities.
Two state agencies, Maryland Department of
the Environment and Maryland DNR, are
already working together to improve the health
of Maryland's streams using Survey data. A
Biocriteria Advisory Committee, composed of
federal and state agencies, environmental
organizations, industry, and academia is
determining how to use the Survey biological
data in water quality regulations. The Com-
mittee will develop a process of using the data
to assess streams for the next Clean Water Act
biennial report to Congress and to prepare
Maryland's list of impaired waters.
How can you help? First, visit Maryland
DNR's web page (see last page) or your local
library and learn more about Maryland
streams and their problems. Then take a long,
hard look at your daily activities to find ways
to lessen your impact on streams and the
Examples of organizations with stream monitoring, protection,
or restoration programs in Maryland. Sb0 the last page for
contact information, I
Audubon Naturalists Society
• Maryland Save Our Streams
Montgomery and Prince Georges County Stream Teams
• Tributary Teams
Trout Unlimited
Maryland's
Tributary
Teams—
comprised of
local citizens,
farmers, business
leaders, and
government
officials
appointed by
the Governor—
are working to
keep your local
streams and
rivers clean
and healthy.
They under-
stand that the
condition of the
Chesapeake
Say can be no
better than the
condition of the
waterways that
link the upland
andscape to
the Bay.
41
-------
It Will Take Teamwork
environment as a whole. Consider joining or
starting a citizens group that conducts activi-
ties that interest you. For example Maryland's
Tributary Teams—partnerships between
citizens, local governments, and State and
Federal agencies—are working throughout
Maryland to reduce nutrient and sediment
pollution and restore habitat in the rivers and
streams that feed the Bay. The ten Teams, one
for each major Chesapeake Bay river basin,
promote best management practices for
farmers, developers and homeowners; educate
their local communities about water quality
and habitat protection; and work with State
and local agencies to prevent pollution and
protect water quality. Grassroots monitoring,
on-the-ground restoration activities, and
teaching others are but a few of the many
potential ways you could get involved.
Finally, consider contacting your elected
leaders to tell them that you are concerned
about protecting and restoring our watersheds
and streams and you want them to represent
your concerns and act accordingly. Local
governments play a critical role in stream
protection and restoration through land use
decisions and local stream restoration and
monitoring efforts. Together we all can save
our priceless streams for many generations
to come.
Protecting our healthy streams before they
need restoration should be a priority.
Photo courtesy ofMD DNR
42
-------
acid mine drainage (AMD) - Acidic, heavy-
metals-laden stream contamination resulting
from the drainage of water that contains acidic
soils and tailings (residues) from the mining
process. Usually associated with surface and
underground coal mining.
acid rain - A term in common use that implies
the deposition of acid materials in wet precipi-
tation (rain, snow, fog) as well as in the dry
precipitation of dust and gases. One source is
the combining of rain and sulphur dioxide
emissions—a by-product of combustion of
fossil fuels.
alkaline - The "opposite" of acid, a solution or
substance having a high concentration of (OH)
ions that can buffer or neutralize an acid. An
example of an alkaline substance is lime used
to neutralize soil acidity on farm fields and
lawns.
amphipod - A small crustacean having a
laterally compressed (i.e. right and left sides
are close together) body.
anadromous - Fish that mature in salt water
and migrate to freshwater to spawn.
arable land - Land suitable for farming.
benthic macroinvertebrate - Aquatic animals
larger than Vz milh'meter, without backbones,
dwelling on or in the bottom of aquatic
environments. Examples are clams, crayfish,
and several types of aquatic insect larvae.
benthos - Biota closely associated with the
bottom of a water body.
Best Management Practice (BMP)-A
practice or combination of practices deter-
mined to be the most effective means of
preventing or reducing the amount of pollution
generated by nonpoint sources to a level
compatible with water quality goals.
base/low - Sustained, low flow in a stream,
primarily from groundwater discharge. Some-
times known as dry weather flow.
biological integrity - The condition of the
biological communities (usually benthic
macroinvertebrates and/or fish) of a waterbody
based on a comparison to a reference that is a
relatively undisturbed system and represents
the best quality to be expected for the
ecoregion.
biota - All of the organisms, including ani-
mals, plants, fungi; and microbes, found in a
given area.
blackwater - A naturally occurring, dark
colored stream, wetland, lake, or river. These
naturally acidic water bodies are darkly
colored by tannins leaching from leaves and
other organic material.
buffer - A solution resistant to pH changes, or
whose chemical makeup tends to neutralize
acids or bases without a change in pH. Surface
waters and soils with chemical buffers are not
43
-------
Glossary
as sensitive to acid deposition as those with
poor buffering capacity.
catadromous - Fish that mature hi fresh water
and migrate to salt water to spawn.
channelization - The artificial enlargement,
straightening, or realignment of a stream
channel.
detritus - Disintegrated or broken up mineral
or organic material in a water body.
dissolved oxygen - Gaseous form of oxygen in
solution with water, abbreviated as DO and
measured as mg/L (milligrams per liter) or
ppm (parts per million).
duff- The organic layer on top of mineral soil
consisting of fallen leaves and other decom-
posing vegetation. Thick layers of duff are
often found on the floors of undisturbed
forests.
eutrophication - The process by which
streams and other water bodies become
enriched with dissolved nutrients, resulting in
increased growth of algae and other micro-
scopic plants.
embayment - An indentation in the shoreline
forming an open bay.
fall line - A line roughly along Interstate 95
joining areas of relatively steep gradient on
several rivers on Maryland's western shore.
The line marks the geographical area where
each river descends from the hilly Piedmont to
the flat and sandy Coastal Plain. It also marks
the limit of upstream commercial navigation.
gabion - A wire cage, usually rectangular,
filled with rock and used in flood control or
for channel and bank stabilization.
habitat - The environment or specific sur-
roundings where plants and annuals live and
grow.
herpetofauna - A collective term for reptiles
and amphibians.
Index ofBiotic Intregity (IBI) - A combina-
tion of measures, or metrics, that describe
community structure, function and pollution
sensitivity and are used to assess the health of
an aquatic ecosystem.
impervious surface - Hard, non-porous
surfaces such as roads, parking lots, and
rooftops that prevent precipitation from
soaking into the ground, thus increasing
surface runoff.
meander - The winding of a stream channel.
migration corridors - Narrow areas of habitat
through which animals may travel to reach
larger habitat areas.
nitrate - The most biologically available form
(NO3) of the nutrient, nitrogen; technically
referred to as nitrate-nitrogen.
non-point source - Pollution that does not
originate from a definable point (e.g., soil or
urban runoff).
nutrients - Any chemical element or com-
pound essential to life, including carbon,
oxygen, nitrogen, phosphorus. When available
in excess quantities, these function as pollut-
ants by fueling abnormally high organic
growth hi waterbodies.
pH - An expression of both acidity and
alkalinity on a scale of 0 to 14, with 7 repre-
senting neutrality; numbers less than 7 indi-
cate increasing acidity and numbers greater
than 7 indicate increasing alkalinity.
phosphorus - An element that serves as a plant
nutrient. Phosphorus is most easily used by
plants in the form of orthophosphate (PO4).
point source discharge - Pollutant discharge
that originates from an identifiable point such
as a pipe.
protists - Single-celled organisms that live
freely or hi small colonies, such as protozoans
and algae. Most protists were formerly classi-
fied as either animals or plants.
riffle - A rocky, shallow, turbulent area of a
stream or river where oxygen is physically
introduced into the water.
riparian buffer - A vegetated protective area
next to a water body serving as a barrier
against polluted runoff and a habitat corridor
for terrestrial animals.
river basin - The land area drained by a river
and its tributaries.
44
-------
Glossary
sediment - Mud, sand, silt, clay, and other
debris from both organic and inorganic
sources that is either suspended in or settles to
the bottom of a water body.
stormwater - Rainwater that reaches a stream
or other water body as surface runoff without
soaking into the ground. The water may enter
the stream by direct runoff, or enter a system
of channels and pipes designed to carry
collected rainwater directly to a stream.
stream order - Numbers assigned to streams
according to their position within a drainage
network. Streams that have no tributaries are
first order; streams that receive only first order
tributaries are second order; and larger
branches that form when two second order
tributaries combine are third order, and so on.
Stream order designations often vary accord-
ing to map scale.
substrate - Submerged mineral or vegetative
surfaces used by biota for attachment, move-
ment, or shelter. Stream substrates include
gravel, cobble, boulder, roots, leaves, and
limbs.
taxa - The plural of taxon. The named classifi-
cation unit to which individuals are assigned.
Higher taxa, such as genus, family, and order,
are those above the species level.
watershed - The area of land from which
rainfall (and/or snow melt) drains into a single
point. Watersheds are sometimes referred to as
drainage basins or drainage areas. Ridges of
higher ground generally form the boundaries
between watersheds. At these boundaries, rain
falling on one side flows toward the low point
of one watershed, while rain falling on the
other side of the boundary flows toward the
low point of a different watershed.
45
-------
-------
This Technical Appendix provides a
synopsis of the approach and methods
used for the Maryland Biological
Stream Survey (the Survey), the sole source of
data for this report. Although information on
Maryland streams is available from other
sources (e.g., other Maryland Department of
Natural Resources programs, Maryland
Department of the Environment, county
agencies, and citizen groups), the Survey's
consistent statistical design and methods em-
ployed throughout Maryland made it the best
program to provide, for the first time, basinwide
and statewide estimates of stream condition.
Details of the Survey's results may be found in
State of the Streams: 1995-1997 Maryland
Biological Stream Survey Results available
from DNR (see page 52).
Overview of the
Survey
The Maryland Biological Stream Survey is
intended to provide statistically unbiased
estimates of the condition of first through
third-order (wadeable) non-tidal streams and
rivers of Maryland on a local (e.g., drainage
basin or county) as well as a statewide scale.
The survey is based on a probabilistic stream
sampling approach where random selections
are made from all sections of streams in the
state that can physically be sampled. The
approach supports statistically valid popula-
tion estimation of variables of interest (e.g.,
largemouth bass densities, miles of streams
with degraded physical habitat, miles of
streams with poor Index of Biotic Integrity
scores, etc.). When repeated, the Survey will
also provide a basis for assessing future
changes in ecological condition of flowing
waters of the state. At present, plans are to
repeat the Survey at regular intervals and
expand the approach to larger streams and
tidal creeks.
Sample Design
The study area for the Survey includes each of
the major drainage basins of the state (assess-
ments for 17 of these are contained in this
report) and a total of three years is required to
sample all basins. For logistical reasons, the
state was divided into three geographic
regions (east, west, and central) with five to
seven basins in each region. Each basin was
sampled at least once during 1995-1997, and
one basin in each region was sampled twice so
that data collected in different years could be
combined into a statewide estimate for each
variable of interest.
The sampling frame for the Survey was
constructed by overlaying basin boundaries on
a map of all blue line stream reaches in the
state as digitized on a U.S. Geological Survey
47
-------
Technical Appendix
48
1:250,000 scale map (see map inside front
cover). Sampling within basins is restricted to
non-tidal, first, second, and third-order
(Strahler stream order system) stream reaches,
excluding unwadeable or otherwise
unsampleable areas. An additional restriction
was that sampling was restricted to public
lands or privately-owned sites where land-
owner permissions were obtained. Overall
success in obtaining landowner permissions
was about 90%.
Sample sites were selected from a comprehen-
sive list of stream reaches in all river basins.
To provide adequate information about each
size of stream, an approximately equal number
of first, second, and third-order streams were
sampled during spring and summer, with the
number of sites of each order hi a basin being
proportional to the number of stream miles (of
an order) hi the entire state. Estimates of
condition (e.g., fish population; stream health
as good, fair, or poor) per mile of stream were
made by extrapolating conditions in the 75 m
sample segment to the number of stream miles
(weighted by order) using 1:250,000 scale
maps. Note: According to the 1:250,000 scale
maps used for the Survey, the total number of
first, second, and third-order stream miles hi
Maryland is 8,800. This number will vary
corresponding to the map scale used.
Sample Collection
and Data Analysis
Benthic macroinvertebrates and water quality
samples were collected during the spring
index period from March through early May,
while fish, herpetofauna, in situ stream
chemistry, and physical habitat sampling were
conducted during the low flow period in the
summer, from June through September.
In the spring, single grab samples of water
were collected and analyzed for pH, acid-
neutralizing capacity (ANC), sulfate, nitrate-
nitrogen, conductivity, and dissolved organic
carbon (DOC) in the laboratory. These vari-
ables primarily characterize the sensitivity of
the streams to acid deposition, and to other
anthropogenic stressors to a lesser extent.
Benthic macroinvertebrates were collected in
the spring using dipnets in the most productive
habitat(s) (e.g., riffles, rootwads, aquatic
vegetation) available in the 75 m segment.
About 2 m2 of stream substrate were sampled
at each site and pooled. Preserved samples
were subsampled (100 +/-10%) in the labora-
tory and identified to genus (if possible).
Habitat assessments were conducted in the
summer using metrics; largely patterned after
EPA's Rapid Bioassessment Protocols and
Ohio EPA's Qualitative Habitat Evaluation
Index (QHEI) in the designated 75 m stream
segments. Riparian habitat measurements were
based on the surrounding area within 5 m of
the segment. Other qualitative measurements
included (1) aesthetic value, based on evi-
dence of human refuse; (2) remoteness, based
on the absence of detectable human activity
and difficulty in accessing the segment; (3)
land use, based on the surrounding area
immediately visible from the segment; (4)
general stream character, based on the shape,
substrate, and vegetation of the segment; and
(5) bank erosion, based on the kind and extent
of erosion present. Quantitative measurements
at each segment included flow, depth, wetted
width, velocity, and stream gradient.
Fish and herpetofauna were sampled during
the summer index period using quantitative,
double-pass electrofishing of the 75 m stream
segments. Blocking nets were placed at each
end of the segment, and one or more direct-
current, backpack electrofishing units were
used to sample the entire segment using
double-pass depletion. All fish captured
during each electrofishing pass were identi-
fied, counted, weighed hi aggregate, and up to
100 individuals of each species were exam-
ined for external anomalies such as lesions
and tumors. All gamefish captured were also
measured for length. Any amphibians, reptiles,
freshwater molluscs,, and submerged aquatic
vegetation either in or near the stream segment
were identified.
Data collected from each sample site were
used to develop statewide and basin-specific
estimates of totals, means (or averages),
proportions, and percentiles for the parameters
of interest. The amount of variability (or
margin of error) associated with any estimate
of a total, mean, proportion, or percentile was
determined by calculating a standard error, a
-------
Technical Appendix
statistic that measures the reliability of an
estimate. A standard error also provides a
statistical basis for deciding if the observed
changes in any parameter of interest over time
or space are significantly different or simply
due to chance alone.
For all phases of the Survey, there was an
ongoing, documented program of quality
assurance/quality control (QA/QC). The QA/
QC program used by the Survey allows for
generation of data with known confidence.
Index of Biotic
Integrity
The steps in developing Indices of Biotic
Integrity (IBIs) were the same for both fish
and benthic macroinvertebrates. Criteria for
both reference and degraded sites were
determined based on water chemistry, physical
habitat, and land use. Ecologically-relevant
geographic strata were determined using
cluster analysis and nonmetric multidimen-
sional scaling. Candidate metrics were evalu-
ated for 1) their ability to discriminate (based
on classification efficiency) between reference
and degraded sites, and 2) for redundancy. The
final suite of metrics used in the IBIs con-
tained those ecologically significant metrics
with the best classification efficiency. Both
IBIs were validated using an independent data
set and overall classification efficiencies were
calculated.
The potential range of IBI scores was from 1.0
to 5.0. Narrative ratings for stream quality
were assigned as in the table below. In this
report, good, fair, and poor ratings of stream
quality were indicated by red, yellow, and
green, respectively.
IBIs were not calculated for selected sampling
sites. For instance, no fish IBIs were calcu-
lated for those sites having upstream water-
sheds less than 300 acres, since small, shallow
streams may naturally support few fish spe-
cies. In these small streams the IBI may
indicate natural conditions rather than anthro-
pogenic stresses. Benthic macroinvertebrate
IBIs were not calculated for sites with small
subsample sizes (i.e., less than 60 organisms
where no obvious impairment was present).
Seventeen percent of all sites with both fish
and benthic macroinvertebrate samples had
benthic IBIs but no fish IBIs.
To provide a more integrated picture of overall
stream health, fish and benthic
macroinvertebrate IBIs were combined (where
both IBIs were available) into a Combined
Biotic Index (CBI). CBI scores were produced
by calculating the mean IBI score for both
benthic and fish IBIs if both were available. If
both were not available, one or the other IBI
was used alone for the CBI. The numbering
and coloring scheme described above for the
IBIs were used for the CBI.
Watersheds
Although the Survey provides information on
a major river basin scale, many readers may
want stream information based on other
watershed designations. For example,
Maryland's Tributary Strategies divide the
state into 10 river basins (Figure Al), while for
some readers, smaller watershed information
may be desired (Figure A2). Table Al provides
a cross reference for major river basins,
Tributary Strategies Basins, and watersheds.
Good (IBI score 4.0
Fair (IBI score 3.0 -
Poor (IBI score 1.0-
-5.0)
3.9)
2.9)
Comparable to reference streams considered to be
minimally impacted.
Comparable to reference conditions, but some aspects
of biological integrity may not .resemble the qualities of
minimally impacted streams.
Significant to strong deviation from reference conditions,
with many to most aspects of biological integrity not
resembling the qualities of minimally - impacted streams.
49
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Technical Appendix
Figure Al.
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51
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for more information on tfie QuaCity of
MarykmcCs Streams...
Maryland Biological
Stream Survey
For current information on the Survey, visit
Maryland DNR's World Wide Web homepage
at http://www.dnr.state.md.us and wade on
over to Bays and Streams. A detailed sum-
mary of three years of Survey sampling is
contained in the report, State of the Streams:
1995-1997 Maryland Biological Stream
Survey Results. Call Ann Smith at l-(877)-
620-8DNR (extension 8611) or (410) 260-
8611 (email: asmith@dnr.state.md.us) for a
copy of this or other Survey reports (expect a
charge to cover printing and postage) or to add
your name to the mailing list for our newslet-
ter, An Eye on Maryland Streams. The
newsletter may also be found online at DNR's
website noted above.
If you would like more information about the
methods used to sample Maryland streams and
analyze data, call Ann Smith at the above
number and ask for the MBSS Sampling
Manual (expect a charge to cover printing and
postage).
Maryland Watershed
and Citizen
Monitoring
Organizations
For information on Maryland's Tributary
Strategies, call l-(877)-620-8DNR (extension
8710) or (410) 260-8710 or check outhttp://
dnr.state.rod.us/Bav/tribstrat. To contact other
watershed organizations in Maryland, go to
the Alliance for the Chesapeake Bay's website
at http://www.acb-online.org. Also, the
Maryland Water Monitoring Council works to
foster cooperation among groups involved in
all types of water monitoring activities in
Maryland. Learn more about the Council at
http://www.mgs.md.gov/mwmc/. For informa-
tion on Maryland's volunteer monitoring
programs, call the state Volunteer Monitoring
Coordinator at (410) 260-8696 or email her at
rbruckler@dnr.state.md.us or visit the DNR
website.
Parris N. Glendening, Governor
Kathleen Kennedy Townsend, Lt. Governor
Sarah J. Taylor-Rogers, Ph. D., Secretary
Stanley K. Arthur, Deputy Secretary
4S2
-------
OMB Control Number: 2090-0019
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53
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