from the mountains to the sea: the state of maryland's...
TRANSCRIPT
From the Mountains to the SeaThe State of Maryland’sFreshwater Streams
United States Office of Research and EPA/903/R-99/023Environmental Protection Development December 1999Agency Washington, DC 20460 www.epa.gov
Map Scale = 1:250,000
Maryland has an intricate network of more than 8,800 miles of freshwater streams. If stretched end-to-end, they would reach from Baltimoreacross the Atlantic Ocean to South Africa.
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From the Mountains to the Sea:The State of Maryland�s Freshwater Streams
Authors
Daniel Boward, Paul Kazyak, Scott StrankoMartin Hurd, Anthony Prochaska
Maryland Department of Natural Resources
Tawes State Office Building, C-2580 Taylor Avenue
Annapolis, MD 21401
with support from
United States Environmental Protection AgencyNational Health and Environmental Effects Research Laboratory
Atlantic Ecology Division
27 Tarzwell DriveNarragansett, RI 02882
and
Region IIIEnvironmental Services Division
1650 Arch StreetPhiladelphia, PA 19103
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NOTICEThe information in this report was funded in part by the United States Environmental ProtectionAgency (Environmental Monitoring and Assessment Program, Office of Research and Develop-ment) through the Atlantic Ecology Division. Support was provided to the Maryland Departmentof Natural Resources by EPA Cooperative Agreement #CR-825488-01-0, T. Pheiffer, ProjectOfficer. The report was subjected to the EPA�s peer and administrative review, and has receivedapproval for publication as an EPA document. Mention of trade names or commercial productsdoes not constitute endorsement or recommendation for use.
The suggested citation for this report is: D.M. Boward, P.F. Kazyak, S.A. Stranko, M.K. Hurd,and T.P. Prochaska. 1999. From the Mountains to the Sea: The State of Maryland�s FreshwaterStreams. EPA 903-R-99-023. Maryland Department of Natural Resources, Monitoring and Non-tidal Assessment Division, Annapolis, Maryland.
ABSTRACTThe Maryland Biological Stream Survey, conducted by the Maryland Department of NaturalResources, sampled about 1,000 randomly-selected sites on first through third order freshwaterstreams throughout Maryland from 1995 to 1997. Biota (fish, benthic macroinvertebrates,herpetofauna) and water chemistry were sampled and physical habitat quality was assessed ateach site. Land use/land cover in the watershed upstream of each site was also determined. Thisreport is intended to present the results of the Survey to a broad array of audiences, including thegeneral public, about the condition of wadeable freshwater streams in Maryland. The report isalso intended to serve as a tool for resource managers and planners for developing policy andtargeting areas for restoration and preservation. For example, the report describes the impact ofurbanization 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 physicalhabitat degradation, including riparian buffer conditions. Other topics include acidification;nutrient enrichment; biodiversity; introduced fish; and rare, threatened, and endangered fishspecies. The reader is provided with a historical context in which to view the current health ofMaryland�s streams. Suggestions are included on how individuals can work with organizations toprotect and restore their local streams.
Key Words: Streams; Maryland; Chesapeake Bay; Environmental Monitoring; Ecological Assess-ment; River Basin; Watershed; Aquatic Life; Biological Diversity; Biological Indicators; WaterQuality; Physical Habitat
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Deer Creek inthe SusquehannaRiver basin.Photo courtesyof MD DNR
Greetings from the Maryland Departmentof Natural Resources and the
U.S. Environmental Protection Agency
Dear Reader:
Maryland�s streams represent a vital, life-giving resource to its citizens. Inaddition to providing clean water to support life in Chesapeake Bay, the world�s mostproductive estuary, our streams provide habitat for a multitude of plants andanimals. From cascading mountain brooks to meandering coastal streams, flowingwaters are sought out for their great beauty, recreational value, and source of tranquilityin a fast-paced world. For these reasons and more, protection and restoration of our aquaticworld 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 ofour aquatic life is very much dependent on the health of our watersheds. What is the currentcondition of our streams? Which human activities have the most effect on our streams andwhere 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 bythe Maryland Department of Natural Resources and supported by the U.S. EnvironmentalProtection Agency.
Maryland is working on stream protection in a variety of ways. Governor Parris N.Glendening�s nationally acclaimed Smart Growth and Neighborhood Conservation initiativerecognizes the link between how we develop our land and the quality of our waterways. Byfinancially supporting new growth only in existing communities or areas locally designated forgrowth, and by permanently preserving forested buffers and other valuable land through thenew Rural Legacy Program, the Smart Growth initiative bolsters efforts to keep Marylandstreams clear and clean.
In the past, water monitoring programs have focused largely on the chemical make-up of ourstreams. 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 newscience of ecological assessment and combining information on water chemistry, physicalhabitat, 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 anew generation of reports on Maryland�s streams, we hope to spur your interest in streams andlead you to an increased awareness and involvement in the protection and restoration of theseirreplaceable natural resources.
Parris N. Glendening Michael McCabeGovernor Acting Deputy AdministratorState of Maryland U.S. Environmental Protection Agency
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From the Mountainsto the Sea...The State ofMaryland�sFreshwater StreamsThis report was produced by the MarylandDepartment of Natural Resources (MD DNR),Resource Assessment Service, Monitoring andNon-tidal Assessment Division, throughCooperative Agreement Number CR-825488-01-0 from U.S. EPA Office of Research andDevelopment.
Authors: Daniel Boward, Paul Kazyak, ScottStranko, Martin Hurd, and Anthony Prochaska
Contributors: We wish to thank severalpeople for their valuable contributions to thisreport. First, the following people contributedgreatly to this report by managing and analyz-ing data and working to develop the indicatorsused here: Mark Southerland, Nancy Roth,and Janis Chaillou of Versar, Inc.; SamStribling, Jeffrey White, and Ben Jessup ofTetra Tech, Inc.; and Ray Morgan andLenwood Hall of the University of Maryland.
We also wish to thank Ron Klauda, PaulMassicot, Ceil Petro, William Jenkins, RobertLundsford, Ray Dintamin, Frank Dawson,John McCoy, Larry Lubbers, and Ken Yetman
of DNR; Tom Pheiffer, Pat Bradley, TomDeMoss, Steve Paulsen, Chuck Kanetsky,Maggie Passmore, and John Stoddard of U.S.Environmental Protection Agency; Ron
Big Elk Creek in the Elk River basinPhoto courtesy of MD DNR
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Preston of the Canaan Valley Institute; KarlBlankenship of the Alliance for the Chesa-peake Bay; Paul Angermeier of the U.S.Geological Survey, and Tom Simpson of theMaryland Department of Agriculture forreviewing the report. Last, but certainly notleast, we thank Ray Morgan, Lenwood Hall,Matt Klein, and Bill Killen of the University ofMaryland for data collection and Derek Wiley,John Stavlas, Natasha Davis, Ann Lenert, DungNguyen, and Lamar Platt of DNR for dataanalysis and presentation.
This report has been reviewed and approvedfor publication by the U.S. Environmental
Acknowledgements
Protection Agency. Approval does not signifythat the contents necessarily reflect the viewsand/or policies of the EPA. Mention of tradenames, products, or services does not convey,and should not be interpreted as conveying,official EPA approval, endorsement, orrecommendation.
On the cover: Hunting Creektumbles over CunninghamFalls in Western Maryland
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Greetings from Maryland Department of Natural Resources andthe 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
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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
Table of Contents
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The purpose of this report is to begin toaddress the current health ofMaryland�s freshwater streams and to
determine the impacts of human activities onthese waters. The data base compiled for thisreport will also be used in the preparation ofMaryland�s next biennial water quality report toCongress. With the availability of this newstatewide information, a logical next step will beto evaluate it�s applicability to regulatory activi-ties. A multi-agency effort is now underway inMaryland to determine how these data on theState�s streams can be used to develop biocriteriafor water quality regulatory programs (see �TheFuture of Maryland�s Streams� section).
Below are the major findings from three years ofstream sampling (1995-1997) by the MarylandBiological Stream Survey (MBSS...or theSurvey). Data from about 1,000 randomly-selected sites were used to assess Maryland�snon-tidal freshwater streams from the Appala-chian Mountains of Garrett County to the LowerEastern Shore. Aquatic animals (fish, benthicmacroinvertebrates, reptiles, and amphibians),physical habitat, and water chemistry wereassessed at each site, as well as land use in theupstream watershed. Indices of Biotic Integrityfor fish and benthic macroinvertebrates wereused to tell us the overall ecological health of thesampled streams. For the first time, we now havea comprehensive and scientifically-defensibletool for telling us how many stream miles, eitherwithin certain river basins or statewide, are
healthy or not. This tool also gives us insight intosome of the causes of stream degradation. For adetailed description of the design and methodsused by the Survey, see the Technical Appendixat the end of this report.
Land Use ImpactsCurrent patterns of urbanization have causedsignificant impacts to Maryland�s streams. Ifurban sprawl continues to consume our forestsand farmlands in the same manner as in thepast, more Maryland streams will likelydegrade in the years to come. For example, thehealth of many streams is largely influencedby the amount of impervious land coverupstream. Three indicators of stream healthhelp us illustrate the harmful effects of urban-ization on stream biota. When watershedimperviousness exceeds 25%, only hardy,pollution-tolerant reptiles and amphibians canthrive, while more pollution-sensitive speciesare eliminated. Above 15% watershed imper-viousness, stream health is never rated good,based on a combined fish and benthicmacroinvertebrate Index of Biotic Integrity.Even low levels of imperviousness affectstreams. When upstream impervious landcover is above 2%, pollution-sensitive brooktrout are never found. Streams most affectedby urbanization are in the Baltimore-Washing-ton Metropolitan portions of the Patapsco andPotomac Washington Metro river basins.
Urbanizationcontinues tothreatenMarylandstreams. If thecurrent rate ofurban sprawlcontinues, moreMarylandstreams willlikely degrade.
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The primary and most widespread source ofnutrients in streams is runoff from farm fields,although excess nutrients enter streams fromseveral other sources, such as acid rain, lawns,golf courses, and septic systems. About 57% ofthe state�s stream miles have unnaturally el-evated nutrient concentrations, and theseconcentrations are generally higher in water-sheds with more agricultural land use. Somesites with greater than 50% agricultural land useupstream contain nitrate concentrations as highas 24 mg/L. Two heavily farmed river basins�the Chester and Middle Potomac�have severalstreams with very high nitrate concentrations.Although excess nitrate in small streams mayproduce an overabundance of algae and aquaticplants, the greatest impacts are realized down-stream in tidal rivers and Chesapeake Bay.
Habitat LossThe loss of high-quality physical habitat iswidespread in Maryland streams due to manyfactors, such as elimination of forested riparian(streamside) buffers and channelization. Only20% of all stream miles in Maryland have goodphysical habitat quality, while 52% are in poorcondition. More than one-quarter (27%) ofMaryland�s stream miles have no vegetatedriparian buffers and thus are poorly protectedagainst stormwater runoff. Because forestedbuffers are a key component of healthy streamsand a healthy Chesapeake Bay, we need toreplant those streamside forests that have beenlost and redouble our efforts to protect thosethat remain.
About 17% of all stream miles statewide arechannelized. Channelized streams are un-
healthy for several reasons, including poorhabitat and elevated water temperatures. Theyalso serve to transport sediment, nutrients, andpollutants to the Chesapeake Bay more rapidlythan streams with natural meandering channelsand healthy biota.
Because of the more than 1,000 migrationbarriers across Maryland streams and rivers,much of the stream habitat once available tomigratory fish is now unaccessible. Forexample, American eel populations have beendiminished by these migration barriers.
AcidityAcid rain is the most important and mostwidespread source of acidity in Marylandstreams, affecting nearly one-fifth of the state�sstream miles. Natural acidification and acidmine drainage each acidify about 3% of allstream miles, while runoff of fertilizers acidi-fies about 4%. Low stream pH has a dramatic
This urban stream channel has been drasti-cally altered to increase stormwater drainage.Photo by Paul Kazyak
Highlights
More than halfof Maryland�s
stream mileshave un-
naturallyelevated
nutrient levels.These levels
are generallyhighest in
watershedswith more
agriculturalland use.
Physicalhabitat
degradation isthe most
widespreadsource ofstress on
Maryland�sstreams, and is
extensive inall but one
river basin.
% IMPERVIOUS COVER% IMPERVIOUS COVER% IMPERVIOUS COVER% IMPERVIOUS COVER% IMPERVIOUS COVER% IMPERVIOUS COVER% IMPERVIOUS COVER
ABOVE 2%BROOK TROUT
DISAPPEAR
ABOVE 2%BROOK TROUT
DISAPPEAR
ABOVE 2%BROOK TROUT
DISAPPEAR
ABOVE 15%BIOTIC INTEGRITY
FAIR OR POOR
ABOVE 15%BIOTIC INTEGRITY
FAIR OR POOR
ABOVE 15%BIOTIC INTEGRITY
FAIR OR POOR
ABOVE 25%ONLY HARDY REPTILES
AND AMPHIBIANS
ABOVE 25%ONLY HARDY REPTILES
AND AMPHIBIANS
ABOVE 25%ONLY HARDY REPTILES
AND AMPHIBIANS
HIGHLOW
11
effect on fish. While streams with pH greaterthan 6 have more than 9,000 fish per streammile, those with pH less than 5 contain no fish.
Biological HealthBased on a combined fish and benthicmacroinvertebrate Index of Biotic Integrity,about 12% of all stream miles in Maryland are ingood condition, 42% are fair, and almost one-half (46%) are poor. Poor streams are consideredunhealthy compared to reference (healthiest)streams. Good and fair streams are consideredhealthy compared to reference streams. Goodstreams are comparable to the highest qualityreference streams and fair streams are compa-rable to the remainder of the reference streams.These two communities of stream animals giveus valuable insights into cumulative impacts(such as acid rain, urban and agricultural runoff,and point source discharges) on our streams.
Biological DiversityIn spite of the many stressors on Maryland�sstreams, they still harbor an incredible diversity ofanimal life. For example, 45 species of amphib-ians and reptiles occupy Maryland streams, with91% of all stream miles having at least onespecies. About 350 types of benthicmacroinvertebrates live among the rocks, roots,wood, sand, and mud of Maryland�s streamswhere they process nutrients and provide food forfish, birds, and mammals.
The southern leopard frog is among the 45species of reptiles and amphibians found inand along Maryland streams during theSurvey.Photo by Brian Stranko
About 100 fish species swim in Marylandstreams�the most abundant is the pollutiontolerant blacknose dace. Six fish species are listedas rare, threatened or endangered and an addi-tional 14 species were found during the Survey atonly a few locations. These species may be at riskand are thus candidates for future listing.
Summary ofStressorsResults of the Survey can help answer impor-tant management questions about the relativeimpacts and geographic extent of differentstressors on Maryland streams (Table 1). Themost extensive and widespread source ofstress is physical habitat degradation, which isextensive in all but one of Maryland�s riverbasins (Elk River). Inadequate riparian buff-ers, unstable stream banks, and channelizationall contribute to physical habitat degradation.
Major water quality stressors include excessnutrients, acid rain, and acid mine drainage.Acid rain is an extensive problem, primarily inWestern Maryland and on the Lower WesternShore, while acid mine drainage problems areconfined to Western Maryland.
There are many stressors that degradeMaryland�s streams. Together, we can allhelp protect those that are still healthy.Photo courtesy of MD DNR
Highlights
Based on thehealth of fishand benthicmacroin-vertebratecommunities,only about onein ten miles ofstreams are ingood condition,while abouthalf are poor.
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Highlights
Table 1. Summary of key stressors to Maryland�s freshwater streams by major river basin. Colors represent thebest 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.
Youghiogheny
North BranchPotomac
Upper Potomac
Middle Potomac
PotomacWash/Metro
Patuxent
Patapsco
Gunpowder
Lower Potomac
West Chesapeake
Bush
Susquehanna
Elk
Chester
Choptank
Nanticoke/Wicomico
Pocomoke
NutrientEnrichment
AcidRain
AcidMine
Drainage
InadequateRiparianBuffer
UnstableBanks
Channelization PoorOverallPhysicalHabitat
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With the Appalachian Mountains tothe west and the beaches of theAtlantic Ocean to the east, Mary-
land is a state of geographic diversity. Oftencalled �America in Miniature,� it is 12,189square miles of rugged mountains, fertilevalleys, rolling hills, and coastal flatlands. It isalso a mosaic of landscapes. Forests, farmfields, suburbs, and dense urban areas arefound throughout the state. And in the centerof it all is Chesapeake Bay...one of Maryland�smost precious natural resources and a truenational treasure.
Maryland�s freshwater streams mirror thisdiversity. From the cascading rapids of MuddyCreek Falls in Garrett County, to the sluggishblackwater* of Zekiah Swamp in CharlesCounty, 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 tosimply stop and contemplate, away from thebustle of daily life. In large measure, they alsodetermine the health of Chesapeake Bay.
In addition to their values to humans, many ofour streams are biological wonderlands�withmyriad species of aquatic plants and animalsthat often go unseen to all but the most astuteobserver. In swiftly-moving water, sluggishsnails scrape tiny colonies of microscopicprotists from rocks. In deep, dark pools,shrimp-like amphipods nibble last fall�s mapleleaves, producing detritus for downstreamfood webs. In a nearby mass of submerged treeroots, a crafty predatory dragonfly larvapounces on and consumes an unsuspectingmayfly...only to be consumed itself by a
MostMarylanderslive within a15 minute walkof a stream.
Maryland�s Diverse Streams.On its way to the Youghiogheny Riverin Garrett County, Muddy Creek Fallstumbles through Swallow Falls StatePark (right). Worcester County�sNassawango Creek (left) meanders tothe Pocomoke River.Photo by Brian Stranko (left) andcourtesy of MD DNR (right)
*terms in the glossary are highlighted at first usage
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voracious brook trout. The trout, of course,may end up as a delicious human dinner.Scenes like these occur every day in many ofour streams and we humans play an increas-ingly large part in directing them; for it is howwe live our lives that determines the health ofthe streams around us.
Before we begin our evaluation of the healthof Maryland�s streams, we must first under-stand the natural diversity of lands within thestate and how we humans have altered theland to suit our purposes. Because streamsmay be quite different depending on theirlocation, we will examine how geology andterrain vary across the state and the manyimpacts resulting from human activities.
Geographic SettingMaryland is divided into three broad geo-graphic areas (Figure 1): the AppalachianPlateau, Piedmont, and Coastal Plain prov-inces. Each has its own combination of soils,geology, vegetation, and terrain that functiontogether to produce different stream types. Tothe east, the flat, low-lying Eastern Shore andthe rolling uplands of the Western Shore makeup the Coastal Plain. This area envelops the
Chesapeake Bay and has soils of sand, silt, orclay and slow-flowing streams with soft sandor gravel bottoms. The Coastal Plain isseparated from the remainder of the state bythe Fall Line, directly west of which are theundulating hills of the Piedmont. Most Pied-mont streams are of moderate slope, with rockor bedrock bottoms. West of the Piedmont, thegeographically diverse Appalachian Plateau(composed of the Blue Ridge, Valley andRidge, and Allegheny Plateau) has expansivelimestone-rich valleys, broadly slopingmountains, and high, steep ridges. Streams inthe Appalachian Plateau are mostly rocky andmay meander through wide floodplains or
Ninety-fivepercent of
Maryland�sstreams
flow intoChesapeake
Bay. Somestreams flow
either towardthe Gulf ofMexico or
through theCoastal Bays
to the AtlanticOcean.
What is the 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, which, from an historical perspective, explains why most Marylanders live and work along this corridor.
Introduction
Figure 1. Maryland has 3 broad geographic areas: the Coastal Plain, Piedmont, andAppalachian Plateau. The Appalachian Plateau has the most diverse landscape.
FallLineAppalachian PlateauAppalachian Plateau
PiedmontPiedmont
Coastal PlainCoastal Plain
Blue Ridge
Valley and Ridge
AlleghenyPlateau
15
Youg
hiog
heny
Chestertown
Cambridge
Cumberland
Frederick Baltimore
Washington, D.C.
Hagerstown
Annapolis
Bush
Chesapeake Bay
Chest
er
Choptank
Elk
Gunpowder
Lower Potomac
MiddlePotomac
otNan ic ke/Wicomico
North
Bran
chPot
om
ac
Oce
anC
oas
tal
Patapsco
Patuxent
Pocomoke
PotomacWashington
Metro
qSus uehannaUpper Potomac
West
Chesap
eake
cascade down steep mountainsides. Yet evenin these mountainous areas, some streamscourse through wetland glades and take onmuch the same character as their EasternShore counterparts.
On a finer scale, Maryland is divided into 18large river basins�the geographic areas ofinterest for this report�each containing anintricate network of streams (Figure 2). TheMiddle Potomac basin is the largest of thesebasins, with 925 square miles and 1,102 stream
miles. The Bush basin is the smallest, with just195 square miles and 186 stream miles. Somebasins like the Patuxent and Patapsco liecompletely within Maryland, but most extendbeyond Maryland into Pennsylvania, Delaware,or West Virginia. By examining stream healthwithin river basins, we provide a tool forassessing the effectiveness of watershedmanagement programs such as Maryland�sTributary Strategies. We also can target certainareas of the state for stream protection andrestoration programs and develop a standardgeographic unit for assessing trends in streamhealth over the years to come.
Maryland is also a mosaic of land uses. Today,only 42% of the state is forested (Figure 3)while prior to European settlement, more than90% of the state was forested. The mostheavily forested river basins are the NorthBranch Potomac and Youghiogheny in West-ern Maryland. Most of the state�s remainingwetlands (about 8% of the total area) areconcentrated on the Lower Eastern Shore. Alittle more than one third (34%) of Maryland�sland is used for farming. The Chester andMiddle Potomac river basins are both more
than one-half farmland. Urban and suburbanland (residential, commercial, industrial,institutional, and extractive) make up about16% of Maryland and are concentrated in theWashington-Baltimore metropolitan area,primarily along the Fall Line and easternportion of the Piedmont in the PotomacWashington Metro and Patapsco basins.Between now and the year 2020, the state�spopulation is expected to increase from5,244,000 to 6,000,000 or about 15%. Thus,the urban and suburban proportion of land willlikely increase to accommodate these newMaryland residents.
About 16% ofMaryland�sland area isurban. Thispercentage isexpected togrow to about21% in thenext 25 years.
Introduction
Figure 2. Maryland has 18 large river basins. All but two, the Youghiogheny and OceanCoastal, 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.
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Figure 3. Maryland is a mosaic of land uses. While most urban land is concentrated in theWashington-Baltimore metropolitan area, much of the Eastern Shore and central part of thestate is agricultural.
How Have OurStreams ChangedSince EuropeanSettlement?To better understand the current state ofMaryland streams, we should look at how theyhave changed in the past three centuries.When European settlers first arrived inMaryland in the early 1600s, our streamsmeandered through mostly unbroken forestsand wetlands. Beavers were abundant�theirponds provided diverse aquatic habitats. Oldtrees died and fell into streams, creating alabyrinth of logs, limbs, and roots that shel-tered fish and other aquatic animals. Rainsoaked into the sponge-like forest floor,slowly replenishing streams with freshgroundwater during dry periods.
As the early settlers dispersed throughoutMaryland after Lord Calvert�s first visit in1634, trees were cut to provide fuel and tomake way for farm fields and settlements.Beavers were eliminated while trying to meetan insatiable demand for fur. To convert
wetlands to farms, streams were straightenedand cleared of wood for better drainage. Overtime, forests along streams were largelyeliminated to maximize the ability of the landto produce crops for the settlers and their farmanimals, and also for export back to Europe.With the trees gone and replaced by tilled andgrazed agricultural lands, soil was washedfrom the land and the streams became warmer,muddier, and more vulnerable to erosion.Nutrients, once retained by the unhurried flowthrough wetlands and percolated through thespongy forest floor, were quickly routed toChesapeake Bay. Eventually, agriculturebecame a dominant feature of Marylandlandscape and remains important today. Thus,these settlers had a much greater impact onMaryland streams than did the Native Ameri-cans who first occupied the land.
As towns became cities during and followingthe Industrial Revolution, many streamsbecame open sewers or were straightened androuted through barren concrete channels toquickly remove storm water from the nearbydeveloped land and minimize flooding. Nolonger could rain soak slowly into the ground.During storms, it quickly ran off parking lots,
Only about 80acres of
Maryland�sforests havenever been
logged.
Humanactivity hasprofoundly
affected riversand streams inall parts of theworld, to suchan extent that
it is nowextremely
difficult tofind any
stream whichhas not beenin some wayaltered, and
probably quiteimpossible tofind any such
river.
� H.B.N. Hynes
Introduction
17
roads, rooftops, and other impervious surfacescarrying with it a load of pollutants. Indeed,streams were viewed primarily as a means toconvey wastes and stormwater to some �out ofsight� downstream place.
The Industrial Revolution also brought anincrease in pollution from the air and fromunderground that continues to acidify ourstreams. From as far away as the Ohio RiverValley and other Midwestern U.S. industrialareas (and as near as our own car exhaustpipes), acidifying chemicals are sent into theatmosphere, only to fall back to the earth asacid rain. In some areas, acid rain has elimi-nated all but the hardiest aquatic life in poorlybuffered streams. Our appetite for energy tofuel our factories and heat our homes resultedin more coal mines, especially in WesternMaryland. Today, drainage from abandonedmines continues to pollute many streams withtoxic acid-laden water.
In summary, there are no pristine freshwaterstreams in Maryland. All have been affectedby humans in some way.
This ReportMany Marylanders want to help protect andrestore our freshwater streams. To do this, weneed to work together. Individual citizens,watershed organizations, businesses, andlocal, state, and federal agencies all have arole to play. But to help our streams, we musthave a benchmark for how healthy they are
now. We must learn what aspects of ourstreams are healthy or unhealthy and work tounderstand what is causing the problems, sowe can improve stream health across the state.
The purpose of this report is to describe thehealth of, and impacts to, Maryland�s freshwa-ter non-tidal streams using information fromthe Maryland Biological Stream Survey, or theSurvey, conducted by Maryland Department ofNatural Resources from 1995 to 1997. Al-though the report paints a picture of overallstream health throughout the state and by riverbasin, many readers may wish to use it as aguide for information on streams in their ownback yard or to learn how they can helpimprove the quality of our streams for them-selves, for their children, and for theirchildren�s children. With a better understand-ing of Maryland streams, we all can learn fromour past mistakes and become more effectivestewards of these wonderful ecosystems.
Introduction
Wilson Mill on Deer Creek.Photo by Paul Kazyak
Impervioussurfaces includeparking lots,rooftops, roads,and sidewalks.They preventrain and meltingsnow fromsoaking into theground, thusincreasingstream flowsduring stormsand reducingstream flowsduring dryperiods.
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Introduction
19
BIOLOGICALINTEGRITY
WATERQUALITYWATER
QUALITYPHYSICALHABITAT
PHYSICALHABITAT
BIOLOGICALINTEGRITY
W hen asked the question, �Howhealthy is this stream?� many ofus first think of drinking its water.
If the water is safe to drink, we may say, thenthe stream is healthy. For many years, streamprotection and restoration efforts focused onlyon water chemistry, without much consider-ation of other ecosystem components. Butthere�s much more to the story. Althoughwater quality certainly is an important part ofoverall stream health, we must also considerthe quality of the physical habitat�thestructure that forms the home for the stream�sinhabitants�and the inhabitants themselves.What is the stream�s biological integrity? Arebiological communities balanced? Are theyfree to move upstream and downstream? Isthere an adequate food supply and breedinghabitat? Are they stressed, and if so what arethe stressors? A stream�s inhabitants (collec-tively called biota) are often the best indica-tors of overall stream health.
Traditional biological stream surveys typicallyfocus on the residents of most concern to thepublic�gamefish such as bass and trout�andoverlook most other biota. These surveys arealso conducted primarily in larger streams andrivers that are likely to support gamefish.Since small streams were largely ignored,information on statewide stream conditions inMaryland has not been available until recently.It is these small streams that make up the
Traditional stream surveys focus on waterquality alone. The best way to assess overallstream health is to combine water qualitywith physical habitat and biological integrity.
majority of our flowing waters. Based on1:250,000 scale maps, almost two-thirds(66%; 5,863 miles) of all non-tidal streammiles in Maryland are first order (Figures 4and 5). It is these small streams, many ofwhich are small enough to jump across, thatoften have the most intimate connection withour backyards, streets, parking lots, and farmfields. Second and third-order streams make
20
1
1
1
1
11
1
1
11
1
11
2
2
2
2
2
3
3
4
up about 17% (1,500 miles) and 8% (690miles) of all non-tidal stream miles respec-tively. Fourth order and larger streams com-prise less than one-tenth (9%; 788 miles) of allstream miles statewide.
In this chapter, we provide a snapshot of thehealth of Maryland�s streams by describingwater quality, physical habitat, and the condi-
tion of aquatic biota for first through third-order streams. We also examine some of themajor stressors affecting stream health result-ing from human activities. From this informa-tion, we hope to create benchmarks of currentstatus against which we can compare streamhealth in the future, enabling us to documenttrends and evaluate the effectiveness of ourstream protection and restoration efforts.
1st Order (66%)
2nd Order (17%)
3rd Order (8%)4th Order andLarger (9%)
Figure 5. Marylandhas over 8,800 milesof non-tidal streams.About two-thirds of thesestream miles are 1st orderwhile less than one-tenthare 4th order or larger. Theaverage 1st order stream isless than 8 feet wide.
The State of Maryland�s Freshwater Streams
Patapsco River Basin
Herring RunWatershed
Figure 4. River basins, watersheds, and stream order. One watershed within the PatapscoRiver basin is that of Herring Run. The numbers beside the streams indicate each stream�sorder. The smallest permanently flowing stream is termed first order, and the union of twofirst order streams creates a second order stream. A third order stream is formed where twosecond order streams join.
WHAT IS AWATERSHED?
A watershedis an area ofland which
drains water(and everything
the watercarries) to a
common outlet.The critical
thing toremember
aboutwatersheds is
that thestreams and
rivers, the hills,and the bottom
lands are allpart of an
inter-connectedsystem. Everyactivity on the
land, in thewater or even
in the air,has the
potential toaffect a
watershed.
21
Many chemical and physical proper-ties of water are important forhealthy streams and healthy Mary-
landers. If our streams are too acidic, toowarm, or overenriched with nutrients, streambiota may suffer or die. If we humans drink orswim in polluted water, our health may alsosuffer. Last, but not least, the future of Chesa-peake Bay depends largely on the quality ofthe water in its streams and rivers. Becausewater runs downhill across the land and intostreams, human activities on the land caneasily impact the quality of small streams andeventually Chesapeake Bay.
This section provides an overview of pollutantsources and the quality of water in Marylandstreams based on a single visit to each stream.This information about water quality, whileuseful, underestimates the extent of problemsassociated with short-term events such asheavy rains.
NutrientsThe primary and most widespread source ofnutrients in streams is excess fertilizer fromfarm fields (Figure 6) and lawns. Nitrate-nitrogen, referred to in this report as nitrate,may either run off the land during storms orsoak into the ground and pollute groundwaterthat may take years or even decades to reach astream. Although nutrients in sewage may
Excess nutrients enter streams in a variety ofways, including runoff of fertilizers from theland or more directly, from animal manure.Photo by Dan Boward
Nitrate is acommonly usedmeasure ofnutrientenrichment. Itis technicallyreferred to asnitrate-nitrogen.
impact many Maryland waterways, sewagetreatment plants are often situated on largerrivers and usually do not affect small streams.
22
< 1 mg/L 1-10 mg/l > 10 mg/L
Septic systems can be a source of nitrate in ruralareas and areas with low density development.Other sources of nitrate in streams includeanimal manure, airborne compounds in smoke-stack emissions, and auto exhaust.
Although excess nitrate in small streams mayproduce an overabundance of algae and otherplants, the most devastating effect is in tidalembayments and Chesapeake Bay. Here, incombination with other nutrients such asphosphorus, nitrate may contribute toeutrophication.
Statewide, about 57% of all non-tidal streammiles have unnaturally elevated nitrate levels(greater than 1 mg/L) and about 2% havenitrate levels greater than 10 mg/L (Figure 7).Nitrate levels greater than 10 mg/L are abovethe human health standard for drinking waterand are considered unsafe for human con-sumption. These streams are in the Nanticoke/Wicomico, Chester, Middle Potomac, andChoptank River basins.
Figure 6. Stream nitrateconcentrations are gener-ally higher in watershedswith more agriculturalland use. Each dot repre-sents one Survey samplingsite.
Figure 7. Streams with nitrate concentration greater than 1 mg/L are considered unnaturallyhigh, compared to streams with minimal human influences. Concentrations greater than 10 mg/Lexceed the human health standard for safe drinking water.
Water Quality
0 50 100
Upper Potomac
Chester
West Chesapeake
BushPotomac Wash. Metro
ChoptankMiddle Potomac
PatapscoNanticoke/Wicomico
SusquehannaGunpowder
Statewide
PocomokeElk
Patuxent
North Branch PotomacYoughiogheny
Lower Potomac
Riv
er B
asin
% Stream Miles
NitrateConcentration
0
Nit
rate
(mg/
L)
% Agricultural Land Use20 40 60 80 100
0
4
8
12
16
20
24
23
AcidityAcid enters streams from four main sources:acid rain, abandoned coal mines, fertilizers, andfrom decomposing leaves and other naturalorganic material. Stream acidity is measured aspH. The lower the pH, the more acidic thestream. A pH less than 5 is considered harmfulto most stream biota, especially fish. When thepH of stream water is too low, gill function, eggdevelopment and larval survival are affected.Also, the concentration of metals such asaluminum become toxic to fish when runoffand stream water become acidified.
Excluding streams with substantial naturalacidity, streams with pH below 5 have no fishwhile streams with pH above 6 have, onaverage, over 9,000 fish per stream mile(Figure 8) based on results of the Survey.Streams with pH between 5 and 6 have anaverage of only 500 fish per stream mile.
The most widespread source of acidity inMaryland streams is acid rain (Figure 9),
impacting about one in five (18%) streammiles, a length of freshwater streams aboutequal to the distance from Baltimore toDenver. Acid rain is formed by reactions ofrain with exhaust and smoke from burnt fossilfuels such as gas, oil, and coal. Rain becomesacidic when dissolved gases form variousacids, such as sulfuric and nitric acid, and fallto earth. Rain is naturally slightly acidic (pHbetween 5.3 and 5.7) because of its dissolvedcarbon dioxide content and to a lesser extentfrom chlorine. However, in some parts ofMaryland, rain has a pH of less than 4, a levelwhich is lethal to most stream biota.
Some streams in Maryland are well-bufferedand thus less susceptible to acid rain impacts.For example, many streams in the Middle andUpper Potomac river basins flow throughlimestone-rich soil and rocks. Their waters are
naturally buffered by these alkaline materials.Streams in other basins are less buffered andunless the sources of acid rain are reduced,these streams may either remain acidic or oneday become acidic.
Water that seeps into streams from abandonedcoal mines is called acid mine drainage orAMD. These streams have a combination oflow pH and high sulfate. They also commonlycarry lethal levels of aluminum and high levelsother metals such as iron and manganese.Since all of Maryland�s coal mines (active andinactive) are restricted to the mountainous
Unnaturalsources ofacidity areperhaps themostdevastatingchemicalimpacts thatthreatenMarylandstream biota.
Smokestack emissions from factories andpower plants (some as far away as Indiana)as well as car and truck exhaust contributeto acid rain in Maryland. More than 80%of all acid rain falling in Maryland comesfrom outside the state.
Water Quality
Figure 8. Low streampH has a dramaticeffect on fish. Al-though streams withpH between 5 and 6contain some fish,those with pH lessthan 5 have none.
pH <5 pH 5-6 pH >6
10000
8000
6000
4000
2000
0
More Acidic Less Acidic
Ave
rage
Num
ber
of F
ish
per
Stre
am M
ile
24
Water Q
uality
Figure 9. Acidic streams and their sources of acidity in Maryland. Acid rain is by far the most widespread source. Streams affected by acid mine drainage arerestricted to the western portion of the state. Streams affected by acid rain are found throughout the state, but mostly in western and southeastern areas.
25
In addition toditching andliming, theeradication ofbeavers frommuch ofMaryland�sEastern Shorehas reducedthe number ofblackwaterstreams. Nolonger heldback by beaverdams andsinuous path-ways, swifterstream flowsnow flush awaythe leaves thatonce turned thewater darkbrown tonearly black.
western part of the state, only about 3% of thetotal stream miles statewide are acidified byAMD (Figure 9). However, in theYoughiogheny and North Branch PotomacRiver basins (the two westernmost river basinsin the state), AMD has acidified about 25%and 15% of the stream miles, respectively.
In some very slow moving streams of southernand eastern Maryland, leaves and otherorganic materials that fall into the water arenot flushed away by the current and may stainthe water much the way tea leaves do, result-ing in brownish or blackish water. Thesesluggish streams have earned the name�blackwater� streams. Along with the stain,leaves also leach acids into the water and thusnaturally acidify the water, but without thetoxic levels of aluminum that occur in streamsthat are affected by acid rain and AMD.
Only about 3% of the non-tidal stream milesin Maryland are naturally acidic (Figure 9).Most are in the Chester, Choptank, Nanticoke/
The water of an unnamed tributary toGeorges Creek, in the North BranchPotomac River basin, is brownish-orangefrom acid mine drainage.Photo by Scott Stranko
Wicomico, and Pocomoke river basins of theCoastal Plain. Historically, there were manymore blackwater streams throughout thisregion, but with channelization and theextensive application of lime on farm fieldsfor the past 100 years, the acidity of manyblackwater streams is likely less today than itwas historically. The biota of blackwaterstreams are adapted to naturally acidic condi-tions. They may actually be threatened by thehigher pH resulting from increased bufferingwhen farm fields are limed.
Fertilizers applied to farm fields, lawns, golfcourses, and other cultivated lands that containlarge amounts of nitrogen may also increasestream water acidity. About 4% of Maryland�sstream miles are acidic primarily due to fertiliz-ers. Most of these streams are on the CoastalPlain in the Choptank, Nanticoke/Wicomico,and Pocomoke river basins (Figure 9).
Zekiah Swamp Run, a blackwater swampin the lower Potomac River Basin.Photo by Scott Stranko
Water Quality
26
Dissolved OxygenJust as sufficient oxygen is necessary forhuman survival, it is also critical for thesurvival of aquatic animals. In most swiftlyflowing streams with riffles, there is plenty ofdissolved oxygen (DO) to support aquaticanimals because the water is aerated as itflows and bubbles over rocks. However, in somesluggish, low gradient streams on the CoastalPlain, DO may drop below the state surfacewater criterion of 5 mg/L (or parts per million).When DO is low, only those organisms adaptedto low DO levels can live. Although DO may benaturally low in many of these slow-flowingstreams, nutrients in fertilizers, runoff fromurban lands, and untreated sewage can act aspollutants when they trigger a series of changesthat lower stream DO levels.
Statewide, 6% of all stream miles have DOlevels less than 5 mg/L. But more than 25% ofthe stream miles in the Chester, Lower Potomac,and Pocomoke river basins have DO levelsbelow this criterion (Figure 10). Seven riverbasins contained no stream miles with low DO.Because DO varies by time of day and season,the single DO sample per site taken by theSurvey during the day underestimates the extentof the low DO problem in Maryland streams.
Water TemperatureWater temperature affects the health ofstreams in many ways. Feeding, reproduction,metabolism, and the abundance of aquaticbiota may all be altered by water that is toowarm or even too cold. Streams that becometoo warm usually contain only organisms ableto tolerate the stresses of heat. Stream tem-peratures also affect the solubility of com-pounds and rate of downstream nutrient flowto Chesapeake Bay.
Runoff of heated water from impervioussurfaces (such as streets, parking lots, androoftops) is a serious and widespread problemin Maryland streams. During summer, rain thatruns off of hot impervious surfaces and flowsdirectly into streams causes temperatures torise abruptly during storms. Even during dryperiods, water temperature is usually morevariable in streams draining urban lands thanthose draining farms and forests. Reasons forthis increased variability include a reducedsupply of cool groundwater and less shadethan in forested streams. Constructed pondsand lakes, especially those located directly onstreams, also affect stream temperaturebecause they are sources of heated water insummer and near-freezing water in winter.
Water Quality
Marylandhas a dissolved
oxygencriterion of5 mg/L for
the protectionof aquatic life.
Figure 10. Percent of stream miles with less than the state water quality criterion of 5 mg/L ofdissolved oxygen. Most impaired streams are in the heavily-farmed Chester and Pocomokebasins.
0
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
Choptank
Middle Potomac
Patapsco
Nanticoke/Wicomico
Susquehanna
Gunpowder
Statewide
Pocomoke
Elk
Patuxent
North Branch Potomac
Youghiogheny
Lower Potomac
Riv
er B
asin
% Stream Miles With DO Less Than 5 mg/L
10 20 30 40 50
27
Water Quality
Urban (10%) Agriculture(17%)
Forest (73%)
Dorsey RunLand Use
Forest (32%)Urban (37%)
Agriculture(31%)
Midway RunLand Use
During 1997, water temperature was continu-ously monitored during summer at about 200Survey sites in 5 river basins. Although state-wide information on stream temperature iscurrently not available from the Survey, twostreams sampled in 1997 in the Patuxent Riverbasin�Dorsey Run and Midway Run�providesome insight into water temperature differencesin streams with different upstream land uses.Both are second-order Coastal Plain streamswith similar widths and depths at the samplingsites, but different upstream land uses. DorseyRun�s watershed is mostly forested (73%), withonly 10% urban land use. The remainder of itswatershed (17%) is agricultural. Midway Run�swatershed, however, is fairly evenly split
among forest (32%), urban (37%), and agricul-tural (31%) land use.
In July, the water in Midway Run becamewarmer in the daytime (and cooler at night)than that in Dorsey Run (Figure 11). Also, thehighest daytime temperatures were reachedmore quickly in Midway Run relative toDorsey Run. Had an afternoon thunderstormoccurred during the period, the differenceswould have been even more pronounced. Thecomparison between these two watershedsgives us insight into how the loss of naturalland cover (forest), increase in the amount ofupstream impervious cover, increase in runofftemperature, and reduced baseflow adverselyaffect water quality and aquatic biota.
Marylandwatertemperaturecriteria fornatural andstocked troutstreams are680 F (200 C)and 750 F(240 C),respectively.
Figure 11. Water temperatures are usually lower and more stable in streams draining forestedland compared to those draining urban land.
15
Tem
pera
ture
(0 C)
July 199720 25 30
15
16
17
18
19
20
21
22
25
24
23
Midway RunDorsey Run
28
Water Quality
29
The riparian zone is the area along the bank ofa stream, river, or other water body. Vegetatedriparian zones may act as a buffer againstpollution and are therefore very important inmitigating the adverse impacts of humanactivities. Although there are several buffertypes, forested riparian buffers provide thebest stream protection. Streamside forestsprovide shade, helping to keep streams cooland dampening fluctuations in stream tem-perature. They provide structures such aswood and roots that improve habitat andstabilize channels. Like other vegetatedbuffers, streamside forests also reduce nutrientand sediment runoff, stabilize stream banks,and provide organic matter that can be used byaquatic animals. Wide forested riparianbuffers protect streams from runoff andgenerally provide better habitat for plants andanimals than narrow buffers. Protecting andrestoring forested riparian buffers on smallstreams is critical since small streams receivemost of their flow from runoff and groundwa-ter while larger streams receive most of theirflow from upstream tributaries that may bepoorly buffered.
Statewide, about 59% of all stream miles haveforested riparian buffers (Figure 12). About40% of the forested stream miles statewidehave buffers greater than 50 meters (164 feet)wide (Figure 13). Almost 60% of the streammiles in the Lower Potomac, North Branch
In addition to clean water, physical habitatis critical for healthy streams. In general,good stream habitats have: 1) wide,
naturally vegetated riparian buffers, 2)meandering channels with stable, naturallyvegetated banks, 3) a variety of substratetypes (such as wood, roots, and rocks), and 4)a variety of water depths and water velocities.Unfortunately, humans have altered naturalstream habitats throughout Maryland, affect-ing both water quality and aquatic life.
Riparian Zone
WHAT ISHABITAT?
The theater inwhich theecological playtakes place; itis a template forthe biota, theirinteractions,and theirevolution.
About 25% ofall stream milesin Marylandlack a vegetatedriparian zoneand thus areunbufferedagainststormwaterrunoff.
FUNCTIONS OF VEGETATEDRIPARIAN BUFFERS
1) Reduce dramatic fluctuations in streamtemperature
2) Reduce nutrient and sediment runoff
3) Stabilize stream banks
4) Provide organic matter for stream foodwebs
5) Provide migration corridors and nestingareas for many terrestrial species
6) Supply wood and roots for channelformation and habitat
30
Potomac, Upper Potomac, and West Chesa-peake basins have wide forested buffers. Incontrast, the Middle Potomac, Pocomoke, andPatapsco basins each have fewer than one-quarter of all stream miles bordered by wideforested buffers. More than one-quarter (27%)of all stream miles in the state are unbufferedand 14% are buffered by vegetation other thanforest, such as abandoned cropland or lawns.
Wood in StreamsAnother widespread impact to stream physicalhabitat quality in Maryland is the loss orremoval of wood, such as logs, limbs, androots, along stream banks and in streamchannels. Destruction of riparian forests,stream channelization, and the removal offallen trees from streams all contribute to this
Figure 12. More than half of all streammiles in Maryland have forested riparianbuffers while just over one-quarter areunbuffered against runoff.
Forest (59%)
OtherVegetation
(14%)
No Buffer (27%)
Figure 13. Forty percent of Maryland�s stream miles are adequately buffered (green shading)by riparian vegetation (trees, shrubs, grass), 25% are only moderately buffered (yellowshading), and 35% have either narrow buffers or none at all (red shading).
100% Stream Miles
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
ChoptankMiddle Potomac
Patapsco
Nanticoke/Wicomico
Susquehanna
Gunpowder
Statewide
Pocomoke
Elk
Patuxent
North Branch Potomac
Youghiogheny
Lower Potomac
Riv
er B
asin
0 50
50 metersand over
6-49 meters 0-5 metersVegetated Riparian
Buffer Width
Physical Habitat
The duff on streamside forest floors and thesoil beneath it act as a sponge, slowingrunoff of nutrients, sediment, and toxiccompounds into streams.Photo by Ken Yetman
Twenty-sevenpercent of allstream milesin Maryland
have novegetatedriparian
buffer.
31
degradation. In many streams, particularly inthe Coastal Plain, wood provides a diversearray of stable habitats and cover for streamanimals. Limbs and roots also trap leaves, avital food supply for many benthic
macroinvertebrates. Undisturbed streams innaturally-forested areas generally contain agreat deal of wood. Without these naturalstructures, banks may become unstable anderode, contributing to sediment and nutrientpollution in downstream rivers and the Chesa-peake Bay.
During the Survey, sampling crews noted thenumber of logs, large tree limbs, and tree rootsat each sample site. Among all river basins inMaryland, counts of wood per stream milerange from 40 in the Upper Potomac to 220 inthe Chester basin. The statewide average is 91(Figure 14). Coastal Plain streams, such asthose in the Chester and Choptank basins, tendto have more wood than streams outside theCoastal Plain, although these numbers arelikely much lower than they were historically.Higher velocities in the steeper gradientstreams outside the Coastal Plain may flushwood from the channel more quickly than inthe more sluggish streams of the Coastal Plain.
ChannelizationAs much of Maryland changed from forestedto developed land, many streams werechannelized to drain farm fields or allow forefficient movement of stormwater from urbanlands. In many areas of the state, channel-ization causes the most severe physical habitatimpacts to streams. During channelization,naturally meandering streams are straightened,
Wood in streams enhances habitat qualityin many ways.Photo by Brian Stranko
Amount of Wood per Stream Mile
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
Choptank
Middle Potomac
Patapsco
Nanticoke/Wicomico
Susquehanna
Gunpowder
Statewide
Pocomoke
Elk
Patuxent
North Branch Potomac
Youghiogheny
Lower Potomac
Riv
er B
asin
0 50 100 150 200 250
Physical Habitat
WOOD ISGOOD
In streams thatdrain farmfields, largelimbs and treetrunks areoften removedto keep thewater flowing.This practicegenerallydecreaseshabitat qualityfor fish andaquaticinvertebrates.
Figure 14. Coastal Plain streams tend to have more wood, roots, and limbs than those outsidethe Coastal Plain. These structures provide valuable habitat for stream animals.
32
riparian vegetation is often cut, and wood isremoved from the stream. Fortunately, manystreams in agricultural areas that werechannelized a century or more ago are nowbeginning to revert to a more natural state.This may be reflected in the higher amounts ofwood in streams of the Coastal Plain, de-scribed above. The most extreme habitatimpacts come in urban areas when streams areconverted to concrete-lined ditches thatprovide minimal habitat for only the hardiestaquatic biota. With straightened channels and
less obstructed flows, channelization alsoincreases the speed at which nutrients andsediment flush from upland streams to down-stream rivers and Chesapeake Bay.
About 17% of all stream miles statewide arechannelized (Figure 15). More than one-halfof the stream miles are channelized in two
Streamchannelization
is moreprevalent inagricultural
areascontainingwetlands.
Stream channelization comes in manyforms. Along farmland (above) manystreams are stripped of their riparianvegetation and straightened. In urban areas(right), they are often lined with concrete.Photos by Niles Primrose (above) and DanBoward (right)
% Stream Miles
Upper Potomac
Chester
West ChesapeakeBush
Potomac Wash. MetroChoptank
Middle Potomac
Patapsco
Nanticoke/Wicomico
SusquehannaGunpowder
StatewidePocomoke
Elk
Patuxent
North Branch Potomac
Youghiogheny
Lower Potomac
Riv
er B
asin
0 50 100
Figure 15. Stream channelization in Maryland is more prevalent in the Coastal Plain and inthe heavily urbanized central part of the state.
Physical Habitat
33
heavily farmed river basins on the EasternShore: the Pocomoke and Nanticoke/Wicomico. Because both basins contain manywetlands, which are not suitable for farming,channelizing streams here to produce arableland was more common than in other basins.About one-quarter of all stream miles in thePatapsco and Potomac Washington Metrobasins are channelized, primarily to drain theexpansive impervious areas in and nearBaltimore and the District of Columbia.
Bank StabilityExcessive stream bank erosion is one sign ofpoor physical habitat with both near and far-reaching consequences. Natural stream banksare stabilized with tree roots, logs, rocks orother materials that minimize erosion evenduring floods. Soil from eroding banks be-comes sediment that is moved by the currentand coats the stream bottom, reducing availablehabitat for benthic macroinvertebrates andspawning areas for fish. Excess sediment in thestream channel also causes bank erosion fartherdownstream. This same sediment clouds thewater, smothers aquatic plants, clogs the gills ofaquatic animals, and carries nutrients contribut-ing to eutrophication in Chesapeake Bay.
Thirty percent of all stream miles statewidehave good bank stability (Figure 16). Morethan two-thirds of the stream miles in the twowesternmost basins, the North BranchPotomac and Youghiogheny, have good bankstability. In contrast, almost three quarters(75%) of all stream miles in both the Gunpow-der and Patuxent basins have poor bankconditions. Streambanks in Western Marylandmay be naturally more stable than those to theeast because rocks (boulders and bedrock) aremore prevalent in and along stream channels
About one-halfof all streammiles inMarylandhave unstablestream banks.
Bank erosion is often most severe wherethere is little vegetated riparian buffer andfew roots to hold the soil.Photo by Dan Boward
Figure 16. Streams in the western part of Maryland tend to have more stable banks thanthose in the east. Erosion from unstable banks contributes to downstream sedimentationproblems in larger rivers and Chesapeake Bay.
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
Choptank
Middle Potomac
Patapsco
Nanticoke/Wicomico
Susquehanna
GunpowderStatewide
PocomokeElk
Patuxent
North Branch PotomacYoughiogheny
Lower Potomac
Riv
er B
asin
Good Fair PoorBank Stability
% Stream Miles0 50 100
Physical Habitat
25 75
34
in the west, and thus provide more stability forstream banks. But in urban areas, such asportions of the Patuxent and Gunpowderbasins, stream channelization and elevatedflows during storms may dramatically increasebank erosion, especially where banks are notwell armored by stable structures such aswood and rocks.
Overall PhysicalHabitat QualityAlthough we may gain insight into specificphysical habitat problems by examining onehabitat measure at a time, it is useful tocombine these measures (e.g., riffle/run
DNR recently developed a provisionalindex to evaluate physical habitatconditions in non-tidal Marylandstreams. By comparing various physicalcharacteristics of one stream to thecharacteristics of least impaired streams,the Physical Habitat Index (PHI)generates a score that rates the overallphysical habitat quality of the sampledstream segment.
quality and instream habitat) to assess theoverall physical habitat condition of a stream.
Based on the provisional Physical HabitatIndex (PHI) developed for the Survey, about20% of all stream miles in the state are ingood condition, while 52% are poor (Figure17). More than three-quarters of all streammiles in the West Chesapeake and Nanticoke/Wicomico basins are in poor condition. Incontrast, the Elk and Susquehanna basins hadthe lowest percentages (11% and 25%, respec-tively) of stream miles rated poor for physicalhabitat quality.
Although the PHI scores should be consideredpreliminary, our results suggest that physicalhabitat degradation is an important, widespreadproblem in Maryland streams. Because riparianbuffer zones are such an important attribute ofstreams and rivers, riparian forests should bestaunchly protected. Replanting protectivevegetation along streams with adequate riparianbuffers is an obvious starting point in therestoration process that should eventuallyincrease PHI scores. Long-term stream moni-toring programs should accompany all restora-tion efforts to evaluate their success.
Figure 17. Statewide, about one-fifth of the stream miles are rated good by the PhysicalHabitat Index while a little over half are rated poor. The Elk River basin contains thehighest percentage of stream miles rated good by this Index. More than one-half the streammiles are rated poor in 11 of the 17 basins.
The PhysicalHabitat Index
incorporatesseveral
measures ofhabitat qualityinto one easily
understoodnumber.
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
Choptank
Middle Potomac
Patapsco
Nanticoke/Wicomico
Susquehanna
Gunpowder
StatewidePocomoke
Elk
Patuxent
North Branch Potomac
Youghiogheny
Lower Potomac
Riv
er B
asin
Good Fair PoorOverall PhysicalHabitat Quality
% Stream Miles0 50 100
Physical Habitat
35
Reptiles andAmphibiansAmphibians and reptiles (collectively calledherpetofauna, or herps) are excellent indica-tors of stream and watershed health. Becausemany of these animals live part of their livesin water and part on land, their survivaldepends not only on water quality but also onthe physical make-up of both environments.
Forty-five species of herps were foundstatewide during the Survey, and 9 out of 10stream miles harbor at least one species. Ofthese 45 species, 29 are either aquatic orintimately dependent upon riparian environ-ments. In general, fewer herp species live inor near Coastal Plain streams than elsewherein the state. The number of species per basinranges from 28 in the Patuxent River basin to10 in the Nanticoke/Wicomico and Bushbasins (Figure 18).
Although several herp species are sensitive toacid rain and other water quality impacts,results from the Survey suggest that, inMaryland, urbanization has a larger impact onherp species diversity, with fewer speciesoccurring in more urbanized areas. Only sevenof the 29 aquatic or riparian species werefound at sites where watershed impervious-ness exceeded 25%, while 22 species occurred
at less urbanized sites (Figure 19). Fourspecies of salamanders occurred exclusively atsites within the least urbanized watersheds(<3% impervious land cover).
Black Rat SnakePhoto by Paul Kazyak
The amount ofurban land ina watershedinfluences whichreptiles andamphibianscan live in itsstreams. Anumber ofspecies can nottolerate thesometimesharshconditionsfound in urbanstreams.
36
Figure 18. Forty-five species of herpetofauna were found during the Survey. No salamanderswere found in the Chester, Pocomoke, or Nanticoke/Wicomico river basins.
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
Choptank
Middle Potomac
Patapsco
Nanticoke/Wicomico
Susquehanna
Gunpowder
Statewide
PocomokeElk
Patuxent
North Branch Potomac
Youghiogheny
Lower PotomacR
iver
Bas
in
Number of Herpetofauna Species
0 5010 20 30 40
GREATER THAN 25%
IMPERVIOUS SURFACE
LESS THAN 3%
IMPERVIOUS SURFACE
3-25%
IMPERVIOUS SURFACE
MOUNTAIN DUSKY SALAMANDER
SEAL SALAMANDER
JEFFERSON SALAMANDER
NORTHERN SLIMY SALAMANDER
AMERICAN TOAD
BLACK RAT SNAKE
COMMON MUSK TURTLE
EASTERN MUD SALAMANDER
FOWLER’S TOAD
LONGTAIL SALAMANDER
NORTHERN LEOPARD FROG
NORTHERN DUSKY SALAMANDER
NORTHERN CRICKET FROG
BULLFROG
COMMON SNAPPING TURTLE
NORTHERN RINGNECK SNAKE
NORTHERN SPRING SALAMANDER
PICKEREL FROG
RED SALAMANDER
RED SPOTTED NEWT
SOUTHERN LEOPARD FROG
SPOTTED TURTLE
WOOD TURTLE
WOOD FROGBULLFROG
COMMON SNAPPING TURTLE
NORTHERN WATER SNAKE
GREEN FROG
NORTHERN TWO-LINED SALAMANDER
EASTERN BOX TURTLE
REDBACK SALAMANDER
NORTHERN RINGNECK SNAKE
NORTHERN SPRING SALAMANDER
PICKEREL FROG
RED SALAMANDER
RED SPOTTED NEWT
SOUTHERN LEOPARD FROG
SPOTTED TURTLE
WOOD TURTLE
WOOD FROG
AMERICAN TOAD
BLACK RAT SNAKE
COMMON MUSK TURTLE
EASTERN MUD SALAMANDER
FOWLER’S TOAD
LONGTAIL SALAMANDER
NORTHERN LEOPARD FROG
NORTHERN DUSKY SALAMANDER
NORTHERN CRICKET FROG
NORTHERN WATER SNAKE
GREEN FROG
NORTHERN TWO-LINED SALAMANDER
EASTERN BOX TURTLE
REDBACK SALAMANDER
BULLFROG
COMMON SNAPPING TURTLE
NORTHERN WATER SNAKE
GREEN FROG
NORTHERN TWO-LINED SALAMANDEREASTERN BOX TURTLE
REDBACK SALAMANDER
Figure 19. Of the 29 aquatic or riparian species of herpetofauna found during the Survey, only7 occurred in heavily-urbanized areas (>25% impervious land cover in the upstream water-shed). Conversely, 4 species of salamanders (in blue) never occurred in urbanized areas (>3%impervious land cover).
Aquatic Life
Frogs and toads Salamanders Turtles, Snakes, andlizards
Mountaindusky, seal,
Jefferson, andnorthern slimy
salamanderswere never
found inurbanized
watershedswith more
than 3%imperviousland cover.
37
Fish
General Description
Maryland�s streams are home to a diversearray of native fishes that are often unnoticedby most stream observers. Numbering morethan 100 species, the total population ofMaryland stream fish exceeds 61 million.From tiny and reclusive shiners to big andbrash catfish, these animals are key compo-nents of balanced stream ecosystems. Becausemany fish consume benthic macroinverte-brates, aquatic plants, or detritus, and arethemselves eaten by larger fish, they providean integral link in stream food chains.
Maryland�s stream fish are exposed to manyphysical and chemical stressors, includingstream channelization, dams, toxic contami-nants, introduced species, and acid rain.Because they often show a range of toleranceto stream degradation, fish communities aregood indicators of overall stream health.These communities include many species thatare unfamiliar to most of us, but are nonethe-less a vital part of our stream ecosystems. TheSurvey provides us with both basic informa-tion on fish communities in our streams (thatcan serve as a baseline for future assessments)and a way to examine how stressors affectboth fish communities and individual fishspecies.
The most abundant (19%) fish in Maryland�sstreams is the pollution-tolerant blacknose dace(Figure 20). Other common species include thepollution-tolerant eastern mudminnow andcreek chub, moderately pollution-tolerantmottled sculpin and tesselated darter, andpollution-intolerant rosyside dace.
Introduced FishIntroduced (sometimes called non-native orexotic) fish species are a common occurrencein Maryland�s streams. As far back as the
1870s, habitat destruction and overharvestdepleted native fish populations to the pointthat the only viable alternative to sustainingrecreational fisheries was thought to be theintroduction of new species. In the last 125years, many species have been stocked in aneffort to boost the variety and quality offishing opportunities in Maryland waters.Some, such as the popular largemouth bassand not-so-popular common carp, have been
There are about12 times asmany stream-dwelling fishin Marylandas there arepeople. Of allthese fish,only 3% aregamefish�those mostfamiliar to us.Rosyside dace
Photo by Brian Stranko
Figure 20. Of the approximately 61million fish in Maryland�s streams, thepollution-tolerant blacknose dace is themost abundant.
Mottled sculpin(13%)
Blacknose dace(19%)
Other species (41%)
Goldfish.Photo by Bob Lunsford
Easternmudminnow(11%)
Creek chub (6%)Rosyside dace (5%)
Tesselated darter (4%)
Aquatic Life
38
highly successful in adapting to Maryland�senvironment. Other non-natives have enteredMaryland streams via other, less intentionalmeans, such as from angler bait buckets andrelease of aquarium pets.
About 20 species of introduced fish live inMaryland�s streams. Some of the species notnative to all or most of the state include:goldfish, fathead minnow, green sunfish,channel catfish, bluegill, brown trout, rainbowtrout, largemouth bass, and smallmouth bass.Almost one-half (45%) of the stream milesstatewide have at least one introduced fish(Figure 21). In general, river basins on theEastern Shore have more introduced fish perstream mile than basins in other areas ofMaryland. About three-quarters of the streammiles in the Elk and Choptank basins haveintroduced fishes, while less than one-quarterof the stream miles in the North BranchPotomac and Upper Potomac basins containthem. Because most introduced fish species inMaryland streams are adapted to life in largestreams and rivers, they are less likely to befound in small streams (Figure 22).
Because many studies have shown that intro-duced species can reduce or even eliminatenative species through competition and preda-tion, proposals to introduce non-native fish in
new areas are now subject to careful review andconsideration before action is taken. Thisapproach should help to minimize adverseeffects on our native fauna in the future.
Figure 21. Almost half of Maryland�s stream miles have introduced fish. They are generallymore common in Coastal Plain streams, especially on the Eastern Shore.
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
Choptank
Middle Potomac
PatapscoNanticoke/Wicomico
Susquehanna
Gunpowder
Statewide
Pocomoke
Elk
Patuxent
North Branch Potomac
Youghiogheny
Lower Potomac
Riv
er B
asin
% Stream Miles
0 8020 40 60
Figure 22. Throughout Maryland, intro-duced fish occur more than twice as oftenin 3rd order streams than in 1st orderstreams.
100
80
60
40
20
0
1 2 3%
of
Stre
am M
iles
wit
h In
trod
uced
Fis
hStream Order
Aquatic Life
Almost one intwo stream
miles inMaryland now
harbors atleast one
introduced(non-native)fish species.
39
A Tale of TwoNativesOnce numbering more than 3 million, onlyabout 300,000 brook trout now live in Mary-land streams. Today, brook trout are found inscattered portions of the Piedmont (Patapsco,Gunpowder, Bush, and Lower Susquehannabasins) and the Allegheny Plateau (North
Branch Potomac and Youghiogheny basins)(Figure 23). No brook trout were found in theCoastal Plain during the Survey, although theyare 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 brooktrout are many, one of the most importantfactors may be water temperature. As treeswere cleared for agriculture and housing,previously forested streams were exposed todirect sunlight as well as hot water runofffrom impervious surfaces like roads androoftops (Figure 24) and warm water dis-charges from ponds and lakes. Today, fewerand fewer streams are cool enough to supportbrook trout, particularly in the eastern half ofthe state. In addition to impervious surfaces,other major threats to the continued existenceof brook trout in Maryland include silt fromnew construction and agriculture, competitionfrom non-native brown trout, loss of forestsalong streams, acid rain, acid mine drainage,and global warming.
The story of American eel in Marylandstreams is much like that of brook trout. Sincethe time of European settlement, distributionsof this species have changed in response toimpacts to their migratory routes. Earlysettlers built many small dams to supply waterpower for mills. Later, more dams were addedfor water supply, flood control, and hydroelec-tric projects, and additional barriers werecreated during road construction. Today, thereare more than 1,000 man-made barriers tomigratory fish in Maryland (Figure 25), and
Two nativeMarylanders,brook troutand Americaneel, were onceabundant andwidespread inour streams.
Brook TroutPhoto by Paul Kazyak
Brook troutwere neverfound in streamswith greaterthan 2%imperviousland cover inthe upstreamwatershed.
Figure 23. Historically, brook trout ranged from the Fall Line to the western border of the state.Current distributions (Survey sites with brook trout) are limited to portions of central andwestern Maryland.
Aquatic Life
40
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access to historical spawning and nurseryhabitat has been greatly reduced for many fishspecies in addition to eels.
An example of the decline of American eelabundance resulting from dam constructioncan be found in the lower Susquehanna River.Prior to the completion of Conowingo Dam in1928, the annual harvest of eels in the riverwas nearly 1 million pounds. Since then, the
annual harvest has been zero�eels have allbut disappeared above the dam (Figure 26).Even in areas without migration barriers,widespread loss of habitat continues to limiteel abundance in Maryland streams. Theresults of the Survey make it clear that addi-tional efforts will be necessary if we are toprotect the living heritage of brook trout andAmerican eel for future generations.
Figure 24. Brook trout are extremelysensitive to the amount of roads, rooftops,and other impervious land cover in awatershed.
Spawning in the depths of the AtlanticOcean, many American eels migrate tosmall freshwater streams in Marylandwhere they mature and spend much oftheir adult lives.
Figure 25. There are more than 1,000 known blockages to fish migration on Maryland�s streams,including dams, culverts, pipe crossings, and gabions. Most documented blockages are east ofthe 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 fishpassage program. Once passage has been restored at these blockages, DNR will focus its effortson blockages in the western part of Maryland.
0Num
ber
of B
rook
Tro
ut p
erSt
ream
Mile
% Impervious Land Cover
01 2 3
500
2500
1500
1000
2000
Aquatic Life
DID YOUKNOW?
American eelsmay live up to30 years. Theoldest one on
record was 85!Eels do not
becomedefinitely maleor female untilthey are about10 inches long.
41
Rare, Threatened,and EndangeredFish Species
Over the past few decades, there has beenincreased concern among scientists, naturalresource managers, and the public over the lossof native plant and animal species locally,regionally, and world wide. Although speciesextinction is a natural phenomenon, it hasincreased dramatically in the last century as aresult of human activities. While newspaperstories often tell of extinctions in far awayplaces such as tropical rain forests, the streamsin our own backyards contain plants andanimals that also need our attention and protec-tion. Rapid, uncontrolled development, acidrain, and a host of other human influencescontribute to the widespread loss of habitatvital to stream dwellers. Concern for many ofthese species is not new. Federal and state
The Endangered Species Act of 1973classifies a species as either endangeredwhen it is in danger of extinction withinthe foreseeable future, or threatenedwhen a species is likely to becomeendangered if its numbers continue todwindle. Maryland has several classifica-tions of rare species that vary accordingto a species� distribution, estimatednumber of populations, and their viability.
Maryland darters are small, inconspicuousbottom-dwelling fish, federally listed asendangered. They were last observed in theDeer Creek watershed (LowerSusquehanna River basin) in 1987 and arebelieved to be extinct. A restriction of theirrange may have occurred with the comple-tion of the Conowingo Dam on theSusquehanna River in 1928. Siltation andwater withdrawl for drinking and irriga-tion are considered to be the principalthreats to the last known population.Photo by Jim Williams
Figure 26. Conowingo Dam blocks the migration of American eel. During the Survey, eelswere found at only two sites upstream of the dam. Because they must swim through the dam�shydroelectric turbines to return to the sea as mature adults, eels that manage to pass throughConwingo dam may be injured or killed and unable to complete their life cycle.
Aquatic Life
42
Species Estimated Number in Maryland
Rainbow darter < 600
Stripeback darterS1 < 600
Banded darter < 600
FlierSU 1,500
Ironcolor shinerS1 3,000
Comely shiner 3,500
Glassy darterS1, E 5,000
LogperchS1 8,000
Striped shiner 10,000
Johnny darter 80,000
American brook lamprey 180,000
Mud sunfishS2 3,500
Swamp darter 10,000
Warmouth 25,000
Silverjaw minnow 60,000
Shield darter 75,000
Banded sunfish 80,000
Brook trout 320,000
Checkered sculpin 475,000
Pearl dace 500,000
Table 2. Rare and endangered Maryland fish species based on the Survey and listed byMaryland DNR. There are about 500,000 pearl dace in Maryland. This may seem like quitea few compared to stripeback darter (<600). Why are pearl dace considered rare if there areso many? In Maryland, pearl dace are found only in streams draining to Antietam Creek andMarsh Run in the Upper Potomac River basin. Because this rare species literally has all itseggs in just a few baskets, it is highly vulnerable to stream degradation.
E Endangered in Maryland S3 Uncommon in Maryland
S1 Extremely rare in Maryland SU Rare-uncertain status in Maryland
S2 Rare in Maryland
Notes on current listings
Each ofthese speciesoccur in lessthan 5% ofMaryland�sstreams
Each ofthese speciesoccur in lessthan 0.5%of Maryland�sstreams
Aquatic Life
43
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 potentialloss of several fish species, a situation thatoften goes unnoticed until it is too late. Resultsof the Survey support the current state listingsof stripeback darter and glassy darter and showthat other species (e.g., flier, ironcolor shiner,glassy darter, logperch, and mud sunfish) mayalso warrant listing (Table 2). Populations ofthese animals are either alarmingly low, or theyare restricted to the few areas where habitatquality is still favorable. Unfortunately, somespecies like the federally endangered Marylanddarter were not found at all by the Survey andmay be extinct.
Although state-listed rare and endangered fishare found in several watersheds throughoutMaryland, some areas, like Zekiah swamp inthe Lower Potomac basin, Tuckahoe Creek inthe Choptank basin, and the Upper PocomokeRiver, have up to four such species in theirwatersheds (Figure 27). Watersheds of theCasselman River in the Youghiogheny basin,Lower Monocacy River in the MiddlePotomac basin, Western Branch of thePatuxent River, and the Lower Pocomoke
River contain up to three rare, threatened orendangered fish species each. No federallylisted threatened or endangered fish specieswere found by the Survey.
BenthicMacroinvertebratesBenthic macroinvertebrates, or more simply�benthos,� are animals without backbones thatare larger than a pinhead. These animals live
There over 350types (taxa) ofbenthicmacroinverte-brates inMarylandstreams.
Predatory hellgrammites live under largerocks in swiftly-moving streams.Photo courtesy of the North AmericanBenthological Society.
Figure 27. Distribution of rare and endangered fish species in Maryland. Watersheds, describedon page 55 of the Technical Appendix, are shaded by the number of species found by the Survey.
Aquatic Life
44
in streams on rocks, logs, leaves, aquaticplants, or in soft sediments. The benthosinclude crayfish, clams and snails, aquaticworms, and aquatic insects such as mayflies,stoneflies, caddisflies, and dragonflies.
Why use benthos to evaluate stream health?Unlike fish, benthos are fairly immobile, sothey are less able to escape the effects ofexcess sediment and other pollutants thatdegrade water quality. Thus, the benthos cangive us reliable information on water andhabitat quality in streams. They represent anextremely diverse group of aquatic animalswith a wide range of tolerances to pollutants.Also, many benthos live for several years,allowing detection of past environmentalproblems.
The number of pollution-sensitive benthicmacroinvertebrate taxa may be used toindicate stream health. Many mayflies,
stoneflies, and caddisflies are generallysensitive to water quality and/or physicalhabitat degradation. These three groups arecollectively referred to as EPT, from theirtaxonomic order names Ephemeroptera,Plecoptera, and Trichoptera. These animalsare often the first to be eliminated from astream once it is polluted or the physicalhabitat degrades.
The number of EPT taxa can provide someinsight into water quality impacts from, forexample, point source discharges or runofffrom urban or agricultural land that addnitrate and other nutrients to Marylandstreams. The average number of EPT taxafound during the Survey declined with in-creased nitrate concentration (Figure 28).
The presence or absence of certain benthicmacroinvertebrate taxa can also help uspinpoint potential stressors in streams. Forexample, the stonefly Acroneuria is pollution-sensitive and survives only among clean rocksin streams with cool, swiftly-moving waterand a good amount of dissolved oxygen. In theMiddle Potomac River basin, which is mostlyagricultural land, these insects were found atonly 9 of the 109 sites sampled and primarily inthe heavily-forested mountains in the westernpart of the basin (Figure 29). Streams here arelikely to be less polluted by sediment, nutrients,pesticides, and herbicides that often enterstreams in runoff from agricultural areas.However, the more pollution-tolerant black fly,Prosimulium, was found throughout the basin�in forested, agricultural, and urban watersheds.These insects can live in degraded streams in themore developed areas of the basin.
Figure 28. The averagenumber of sensitive benthicmacroinvertebrate taxa (EPTtaxa) declines with increasednitrate concentration.Streams with nitrate <1 mg/Lare considered to havenatural nitrate levels.
10
1<1 1-4 4-7 >7
Nitrate (mg/L)
Ave
rage
Num
ber
of E
PT
Tax
a
And the winner is...
Of all sites sampled in the Survey,Buffalo Run in the Youghiogheny Riverbasin had the highest diversity with 37benthic macroinvertebrate taxa. Thewatershed upstream of this second orderstream in Garrett County was mostlyforested (67%), with some agriculture(33%). Conversely, Moores Run in thePatapsco River basin (Baltimore City)had only one taxon. This second orderstream drains a mostly urban (83%)watershed.
Aquatic Life
Becausebenthic
macroinverte-brates are
found inalmost every
Marylandstream andare easy tocatch with
inexpensiveequipment,
severalvolunteer
monitoringgroups use
them asindicators of
stream health.
5
45
Index of BioticIntegrityAlthough we can evaluate individual aspectsof stream health, such as the presence orabsence of rare, threatened, or endangered fishspecies, or the number of pollution-sensitivebenthic macroinvertebrates, it is quite usefulto combine several measures of stream com-munity health into one overall value, or index.By using an index, complex ecological infor-mation can be summarized and stream healthcan be rated as either good, fair, or poor.
One such index of the overall health of streamcommunities is the Index of Biotic Integrity,or IBI. Benthic macroinvertebrate and fish IBIsdeveloped for the Survey reflect the structureand function of these communities as comparedto reference (healthiest) streams within asimilar region. Streams rated good or fair bythe IBIs are considered healthy compared tothe reference streams. Good streams arecomparable to the highest quality referencestreams and fair streams are comparable to theremainder of the reference streams. Poorstreams are considered unhealthy compared toreference streams. These Indices have severalmeasures or metrics that describe, for example,the number of species (a measure of communitystructure), the feeding mode (a measure ofcommunity function), pollution sensitivity, andproportion of introduced species, and thusprovide us with a picture of overall ecological
stream health. The EPT Index, described in thepreceding section, is one component of thebenthic macroinvertebrate IBI. See the Techni-cal Appendix for a more detailed explanation ofthe fish and benthic IBIs.
Based on the benthic macroinvertebrate IBI,only 11% of all non-tidal stream miles inMaryland are in good condition, while justover half (51%) are in poor condition (Figure30). This index rates the remaining streammiles (38%) as fair. The fish IBI paints asomewhat different picture of the health ofMaryland streams. One-fifth (20%) of allstream miles are rated good, almost one-third(29%) are rated poor, and 26% of the streammiles are rated fair by the fish IBI. Becausebenthic macroinvertebrates and fish havedifferent pollution sensitivities, habitatrequirements, and abilities to avoid pollution,it is reasonable to expect that these two IBIsmay not always agree at the same stream site.
By combining the benthic and fish IBIs, weget a more integrated picture of overall streamhealth 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 allstream miles poor, 42% fair, and 12% good(Figure 31). Using this combined Index, thePotomac Washington Metro basin has thesmallest percentage of stream miles rated good(<1%) while the Bush has the highest percent-age in this category (25%).
Figure 29. In the MiddlePotomac basin, pollution-sensitive stoneflies werefound primarily in forestedareas while pollution-tolerant black flies werefound in all areas of thebasin.
Aquatic Life
The Index ofBiotic Integrityprovides uswith an overallpicture ofstream healthby quantifyingthe conditionof fish andbenthicmacroinverte-bratecommunities.
Black Fly (Prosimilium)
Stonefly (Acroneuria)
Present at siteAbsent from site
UrbanForestedAgriculturalWetlands
46
Urbanization is perhaps the greatest stressor tothe biota of Maryland streams. As noted in thebrook trout example on page 37, the impactsfrom urbanization to stream habitats and waterquality are often so severe that even minimalamounts cause degradation and loss of re-sources. This fact is supported by the relation-ship between the percent of impervious landcover upstream of Survey sample sites and theCBI (Figure 32). When watershed impervious-ness exceeds 15%, stream quality was neverrated good, thus illustrating one of the naturalresource benefits of focusing growth into areas
that are already urbanized and limiting theamount of impervious land cover throughoutthe state.
The Future ofMaryland�s StreamsAs we look ahead to the future of Marylandstreams, it is critical to reflect on the past andevaluate the present. Although we are movingin the right direction in many ways, such ascontrolling non-point source runoff, pointsource discharges, and providing passage to
Figure 31. The provisional Combined Biotic Index (CBI) provides a picture of stream healthbased on both benthic and fish communities. Statewide, almost one-half of all stream miles are inpoor condition based on this Index.
Fair Poor
% Stream Miles100
Aquatic Life
Figure 30. The health of Maryland�s streams as indicated by the fish and benthicmacroinvertebrate Indices of Biotic Integrity (IBIs). Fewer stream miles are rated good andmore stream miles are rated poor by the benthic IBI. Fish IBIs were not calculated for smallstreams (watershed upstream <300 acres) while benthic IBIs were not calculated for streamswith very low subsample sizes (<60 organisms).
No IBI(26%)
Good(19%)
Fair(26%)
Poor(29%)
Poor(51%)
No IBI(<1%)
Good(11%)
Fair(38%)
Fish IBI Benthic IBI
Good
Upper Potomac
Chester
West Chesapeake
Bush
Potomac Wash. Metro
Choptank
Middle Potomac
PatapscoNanticoke/Wicomico
Susquehanna
Gunpowder
Statewide
Pocomoke
Elk
Patuxent
North Branch Potomac
Youghiogheny
Lower Potomac
Riv
er B
asin
0 50
Combined BioticIndex
47
migratory fish, human activities continue toimpact Maryland streams, Chesapeake Bay,and, although often ignored, even the Gulf ofMexico. Fish communities are unhealthy in
more than a quarter of our stream miles, whilemore than half of all stream miles havebenthic macroinvertebrate communities inpoor condition.
Beyond the community level, 7 of the 100 or sofreshwater fish species in Maryland are af-forded special protection because they are indanger of extinction and an additional 15species 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. Americaneel and brook trout, once abundant in Marylandstreams, are now restricted in number anddistribution. Clearly, there is much work ahead ifwe are to save our remaining resources andattempt to restore some of what we have lost.
More than one-third of our stream miles havelittle or no vegetated riparian buffers. While
Water is themost criticalresource issueof our lifetimeand ourchildren�slifetime. Thehealth of ourwaters is theprincipalmeasure ofhow we liveon the land.� Luna Leopold
there is increasing interest in protecting andreestablishing riparian buffers, forested areasalong streams continue to be lost, even onpublic lands. Although achieving Maryland�sgoal of 600 additional miles of forested streambuffers by the year 2010 (Maryland�s StreamReleaf Program) will be a landmark achieve-ment, much more needs to be done. We alsoneed to recognize the vital importance ofallowing trees that die naturally to fall intostreams, where they create more habitat inthose streams and rivers that already haveforested riparian buffers.
Conversion of farmland and forest into urbanareas continues at a rapid pace in Maryland.At the current rate of population growth anddevelopment, an area the size of BaltimoreCounty (612 square miles or about 5% ofMaryland�s total area) will be urbanized in thenext 25 years. The old adage that �an ounce ofprevention is worth a pound of cure� isespecially appropriate when considering theeffects of urbanization�we now know thatliving resources in streams are impacted evenat low levels of urbanization and that theseimpacts become pronounced when the amountof impervious land cover exceeds 15% of awatershed. Another problem is populationgrowth. With the projected rate of populationincrease in Maryland, many streams in thestate will become more degraded by thecumulative impacts of too many people.
The future health of many Maryland streamswill be dependent on our commitment toredirect population growth and developmentinto existing urban areas rather than continueto �sprawl� into forested and agriculturalareas. Streams that are currently healthyshould be protected�the most cost-effective
Youghiogheny River GorgePhoto courtesy of MD DNR
Figure 32. The amount ofimpervious land coverupstream of a stream siteinfluences the CombinedBiotic Index (CBI), a biologi-cal measure of stream health.When watershed impervious-ness exceeds 15%, streamhealth was never rated good.
15
0<5 5-10 10-15 15-20 20-25 25-30 >30
% Impervious Land Cover
% o
f Si
tes
Rat
edG
ood
by t
he C
BI
The Future of Maryland�s Streams
48
strategy. But, for those streams that have beendegraded by urbanization, intense agriculturalpractices, 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 recoverand function at a self-sustaining level. Thefirst and most important step in a restorationaction is to halt, wherever possible, thedisturbance that is causing degradation.Restoration actions can range from inexpen-sive, passive approaches that involve littlemore than removal of the disturbances sonatural recovery can occur, to much morecostly and active restoration measures wherethe stream cannot recover naturally. Urbanstream restoration projects can effectivelyimprove portions of badly degraded streams.However, where substantial intervention isneeded, these efforts can be costly (as much as$1 million per mile of stream).
Today, many of the opportunities for streamrestoration are also found in agricultural areas.Based on our experience during the Survey,farmers in Maryland have expressed a generalwillingness to modify the way they farm. Forexample, many are willing to use Best Manage-ment Practices, such as no-till farming andcontour plowing, to better protect and restoreaquatic resources, but not at the expense of theirlivelihoods. A clear challenge for the future willbe to protect and restore farmland streamswithout jeopardizing our farming heritage.
In addition to impacts from land development,our growing and seemingly insatiable demandfor energy is a current and future problem forMaryland streams. As Marylanders continuetheir exodus from existing urban areas and moveinto larger homes that are farther from theirworkplaces, fuel consumption and the number ofvehicle miles traveled in Maryland increasesannually, and the amount of nitrogen and acidsadded to streams from the atmosphere continuesto be a major problem. New regulations for airand water quality management have helped toreduce some types of impacts, but significantproblems remain. For example, almost one-fifthof Maryland�s stream miles are affected by acidrain, and with expected increases in populationand vehicle miles, the amount of nitrogen thatends up in streams and the Chesapeake Bay isexpected to increase each year.
In spite of all the problems with Maryland�sstreams, their future is bright in many respects.We have many opportunities to protect ourhealthy streams, improve those that are un-healthy, and change our lifestyles to reduce our�footprint� on our streams. Results of the Surveyprovide valuable information for tracking theseimprovements, but we�ll need to work togetherto make it happen.
It Will TakeTeamworkWe Marylanders need to work together toprotect and restore the health of our streams.If we are to do this effectively, we need toacknowledge the extent of the problem andeducate others. Then, we need to make asustained commitment to change our presentbehavior and correct the mistakes of the past.Our children, grandchildren, and theirgrandchildren are all depending on us to dothe right thing.
Results of the Survey have helped demonstratethat there are no longer any pristine streams inMaryland. A disturbing number of streams areunhealthy, and rarely is there a single cause ofthe degradation we observed. However, inspite of water quality and habitat problemsrevealed by the Survey, many healthy streamsstill exist and protection of these streamsshould be a top priority.
Replanting riparian buffers is one of manyways we can work together to restore ourstreams.Photo courtesy of MD DNR
It Will Take Teamwork
There aremany wayswe can allhelp keepour streamshealthy:
� don�t over-fertilizelawns
� stop septicsystemseepage
� plant trees,shrubs, andground coverto reducerunoff
49
� Audubon Naturalists Society
� Maryland Save Our Streams
� Montgomery and Prince Georges County Stream Teams
� Tributary Teams
� Trout Unlimited
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 stateand local agencies as well as concerned citizens. Since completion of the project, the oncebadly 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 challengeof protecting and restoring streams for futuregenerations of Marylanders should be consid-ered as a wealth of opportunities.
Two state agencies, Maryland Department ofthe Environment and Maryland DNR, arealready working together to improve the healthof Maryland�s streams using Survey data. ABiocriteria Advisory Committee, composed offederal and state agencies, environmentalorganizations, industry, and academia is
It will Take Teamwork
Examples of organizations with stream monitoring, protection,or restoration programs in Maryland. See the last page for
contact information.
determining how to use the Survey biologicaldata in water quality regulations. The Com-mittee will develop a process of using the datato assess streams for the next Clean Water Actbiennial report to Congress and to prepareMaryland�s list of impaired waters.
How can you help? First, visit MarylandDNR�s web page (see last page) or your locallibrary and learn more about Marylandstreams and their problems. Then take a long,hard look at your daily activities to find waysto lessen your impact on streams and the
Maryland�sTributaryTeams�comprised oflocal citizens,farmers, businessleaders, andgovernmentofficialsappointed bythe Governor�are working tokeep your localstreams andrivers cleanand healthy.They under-stand that thecondition of theChesapeakeBay can be no better than thecondition of thewaterways thatlink the uplandlandscape tothe Bay.
50
It Will Take Teamwork
Protecting our healthy streams before theyneed restoration should be a priority.Photo courtesy of MD DNR
environment as a whole. Consider joining orstarting a citizens group that conducts activi-ties that interest you. For example Maryland�sTributary Teams�partnerships betweencitizens, local governments, and State andFederal agencies�are working throughoutMaryland to reduce nutrient and sedimentpollution and restore habitat in the rivers andstreams that feed the Bay. The ten Teams, onefor each major Chesapeake Bay river basin,promote best management practices forfarmers, developers and homeowners; educatetheir local communities about water qualityand habitat protection; and work with Stateand local agencies to prevent pollution andprotect water quality. Grassroots monitoring,on-the-ground restoration activities, andteaching others are but a few of the manypotential ways you could get involved.
Finally, consider contacting your electedleaders to tell them that you are concernedabout protecting and restoring our watershedsand streams and you want them to representyour concerns and act accordingly. Localgovernments play a critical role in streamprotection and restoration through land usedecisions and local stream restoration andmonitoring efforts. Together we all can saveour priceless streams for many generationsto come.
51
acid mine drainage (AMD) - Acidic, heavy-metals-laden stream contamination resultingfrom the drainage of water that contains acidicsoils and tailings (residues) from the miningprocess. Usually associated with surface andunderground coal mining.
acid rain - A term in common use that impliesthe deposition of acid materials in wet precipi-tation (rain, snow, fog) as well as in the dryprecipitation of dust and gases. One source isthe combining of rain and sulphur dioxideemissions�a by-product of combustion offossil fuels.
alkaline - The �opposite� of acid, a solution orsubstance having a high concentration of (OH)ions that can buffer or neutralize an acid. Anexample of an alkaline substance is lime usedto neutralize soil acidity on farm fields andlawns.
amphipod - A small crustacean having alaterally compressed (i.e. right and left sidesare close together) body.
anadromous - Fish that mature in salt waterand migrate to freshwater to spawn.
arable land - Land suitable for farming.
benthic macroinvertebrate - Aquatic animalslarger than ½ millimeter, without backbones,dwelling on or in the bottom of aquaticenvironments. Examples are clams, crayfish,and several types of aquatic insect larvae.
benthos - Biota closely associated with thebottom of a water body.
Best Management Practice (BMP) - Apractice or combination of practices deter-mined to be the most effective means ofpreventing or reducing the amount of pollutiongenerated by nonpoint sources to a levelcompatible with water quality goals.
baseflow - Sustained, low flow in a stream,primarily from groundwater discharge. Some-times known as dry weather flow.
biological integrity - The condition of thebiological communities (usually benthicmacroinvertebrates and/or fish) of awaterbody based on a comparison to a refer-ence that is a relatively undisturbed systemand represents the best quality to be expectedfor the ecoregion.
biota - All of the organisms, including ani-mals, plants, fungi, and microbes, found in agiven area.
blackwater - A naturally occurring, darkcolored stream, wetland, lake, or river. Thesenaturally acidic water bodies are darklycolored by tannins leaching from leaves andother organic material.
buffer - A solution resistant to pH changes, orwhose chemical makeup tends to neutralizeacids or bases without a change in pH. Surfacewaters and soils with chemical buffers are not
52
as sensitive to acid deposition as those withpoor buffering capacity.
catadromous - Fish that mature in fresh waterand migrate to salt water to spawn.
channelization - The artificial enlargement,straightening, or realignment of a streamchannel.
detritus - Disintegrated or broken up mineralor organic material in a water body.
dissolved oxygen - Gaseous form of oxygen insolution with water, abbreviated as DO andmeasured as mg/L (milligrams per liter) orppm (parts per million).
duff - The organic layer on top of mineral soilconsisting of fallen leaves and other decom-posing vegetation. Thick layers of duff areoften found on the floors of undisturbedforests.
eutrophication - The process by whichstreams and other water bodies becomeenriched with dissolved nutrients, resulting inincreased growth of algae and other micro-scopic plants.
embayment - An indentation in the shorelineforming an open bay.
fall line - A line roughly along Interstate 95joining areas of relatively steep gradient onseveral rivers on Maryland�s western shore.The line marks the geographical area whereeach river descends from the hilly Piedmont tothe flat and sandy Coastal Plain. It also marksthe limit of upstream commercial navigation.
gabion - A wire cage, usually rectangular,filled with rock and used in flood control orfor channel and bank stabilization.
habitat - The environment or specificsurroundings where plants and animals liveand grow.
herpetofauna - A collective term for reptilesand amphibians.
Index of Biotic Intregity (IBI) - A combina-tion of measures, or metrics, that describecommunity structure, function and pollutionsensitivity and are used to assess the health ofan aquatic ecosystem.
impervious surface - Hard, non-poroussurfaces such as roads, parking lots, androoftops that prevent precipitation fromsoaking into the ground, thus increasingsurface runoff.
meander - The winding of a stream channel.
migration corridors - Narrow areas of habitatthrough which animals may travel to reachlarger habitat areas.
nitrate - The most biologically available form(NO
3) of the nutrient, nitrogen; technically
referred to as nitrate-nitrogen.
non-point source - Pollution that does notoriginate from a definable point (e.g., soil orurban runoff).
nutrients - Any chemical element or com-pound essential to life, including carbon,oxygen, nitrogen, phosphorus. When availablein excess quantities, these function as pollut-ants by fueling abnormally high organicgrowth in waterbodies.
pH - An expression of both acidity andalkalinity on a scale of 0 to 14, with 7 repre-senting neutrality; numbers less than 7 indi-cate increasing acidity and numbers greaterthan 7 indicate increasing alkalinity.
phosphorus - An element that serves as aplant nutrient. Phosphorus is most easily usedby plants in the form of orthophosphate (PO
4).
point source discharge - Pollutant dischargethat originates from an identifiable point suchas a pipe.
protists - Single-celled organisms that livefreely or in small colonies, such as protozoansand algae. Most protists were formerly classi-fied as either animals or plants.
riffle - A rocky, shallow, turbulent area of astream or river where oxygen is physicallyintroduced into the water.
riparian buffer - A vegetated protective areanext to a water body serving as a barrieragainst polluted runoff and a habitat corridorfor terrestrial animals.
river basin - The land area drained by a riverand its tributaries.
Glossary
53
sediment - Mud, sand, silt, clay, and otherdebris from both organic and inorganicsources that is either suspended in or settles tothe bottom of a water body.
stormwater - Rainwater that reaches a streamor other water body as surface runoff withoutsoaking into the ground. The water may enterthe stream by direct runoff, or enter a systemof channels and pipes designed to carrycollected rainwater directly to a stream.
stream order - Numbers assigned to streamsaccording to their position within a drainagenetwork. Streams that have no tributaries arefirst order; streams that receive only first ordertributaries are second order; and largerbranches that form when two second ordertributaries combine are third order, and so on.Stream order designations often vary accord-ing to map scale.
substrate - Submerged mineral or vegetativesurfaces used by biota for attachment, move-ment, or shelter. Stream substrates includegravel, cobble, boulder, roots, leaves, andlimbs.
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 whichrainfall (and/or snow melt) drains into a singlepoint. Watersheds are sometimes referred to asdrainage basins or drainage areas. Ridges ofhigher ground generally form the boundariesbetween watersheds. At these boundaries, rainfalling on one side flows toward the low pointof one watershed, while rain falling on theother side of the boundary flows toward thelow point of a different watershed.
Glossary
54
Glossary
55
This Technical Appendix provides asynopsis of the approach and methodsused for the Maryland Biological
Stream Survey (the Survey), the sole source ofdata for this report. Although information onMaryland streams is available from othersources (e.g., other Maryland Department ofNatural Resources programs, MarylandDepartment of the Environment, countyagencies, and citizen groups), the Survey�sconsistent statistical design and methods em-ployed throughout Maryland made it the bestprogram to provide, for the first time, basinwideand statewide estimates of stream condition.Details of the Survey�s results may be found inState of the Streams: 1995-1997 MarylandBiological Stream Survey Results availablefrom DNR (see page 57).
Overview of theSurveyThe Maryland Biological Stream Survey isintended to provide statistically unbiasedestimates of the condition of first throughthird-order (wadeable) non-tidal streams andrivers of Maryland on a local (e.g., drainagebasin or county) as well as a statewide scale.The survey is based on a probabilistic streamsampling approach where random selectionsare made from all sections of streams in thestate that can physically be sampled. The
approach supports statistically valid popula-tion estimation of variables of interest (e.g.,largemouth bass densities, miles of streamswith degraded physical habitat, miles ofstreams with poor Index of Biotic Integrityscores, etc.). When repeated, the Survey willalso provide a basis for assessing futurechanges in ecological condition of flowingwaters of the state. At present, plans are torepeat the Survey at regular intervals andexpand the approach to larger streams andtidal creeks.
Sample DesignThe study area for the Survey includes each ofthe major drainage basins of the state (assess-ments for 17 of these are contained in thisreport) and a total of three years is required tosample all basins. For logistical reasons, thestate was divided into three geographicregions (east, west, and central) with five toseven basins in each region. Each basin wassampled at least once during 1995-1997, andone basin in each region was sampled twice sothat data collected in different years could becombined into a statewide estimate for eachvariable of interest.
The sampling frame for the Survey wasconstructed by overlaying basin boundaries ona map of all blue line stream reaches in thestate as digitized on a U.S. Geological Survey
56
1:250,000 scale map (see map inside frontcover). Sampling within basins is restricted tonon-tidal, first, second, and third-order(Strahler stream order system) stream reaches,excluding unwadeable or otherwiseunsampleable areas. An additional restrictionwas that sampling was restricted to publiclands or privately-owned sites where land-owner permissions were obtained. Overallsuccess in obtaining landowner permissionswas about 90%.
Sample sites were selected from a comprehen-sive list of stream reaches in all river basins.To provide adequate information about eachsize of stream, an approximately equal numberof first, second, and third-order streams weresampled during spring and summer, with thenumber of sites of each order in a basin beingproportional to the number of stream miles (ofan order) in the entire state. Estimates ofcondition (e.g., fish population; stream healthas good, fair, or poor) per mile of stream weremade by extrapolating conditions in the 75 msample segment to the number of stream miles(weighted by order) using 1:250,000 scalemaps. Note: According to the 1:250,000 scalemaps used for the Survey, the total number offirst, second, and third-order stream miles inMaryland is 8,800. This number will varycorresponding to the map scale used.
Sample Collectionand Data AnalysisBenthic macroinvertebrates and water qualitysamples were collected during the springindex period from March through early May,while fish, herpetofauna, in situ streamchemistry, and physical habitat sampling wereconducted during the low flow period in thesummer, from June through September.
In the spring, single grab samples of waterwere collected and analyzed for pH, acid-neutralizing capacity (ANC), sulfate, nitrate-nitrogen, conductivity, and dissolved organiccarbon (DOC) in the laboratory. These vari-ables primarily characterize the sensitivity ofthe streams to acid deposition, and to otheranthropogenic stressors to a lesser extent.
Benthic macroinvertebrates were collected inthe spring using dipnets in the most productive
habitat(s) (e.g., riffles, rootwads, aquaticvegetation) available in the 75 m segment.About 2 m2 of stream substrate were sampledat each site and pooled. Preserved sampleswere subsampled (100 +/- 10%) in the labora-tory and identified to genus (if possible).
Habitat assessments were conducted in thesummer using metrics largely patterned afterEPA�s Rapid Bioassessment Protocols andOhio EPA�s Qualitative Habitat EvaluationIndex (QHEI) in the designated 75 m streamsegments. Riparian habitat measurements werebased on the surrounding area within 5 m ofthe segment. Other qualitative measurementsincluded (1) aesthetic value, based on evi-dence of human refuse; (2) remoteness, basedon the absence of detectable human activityand difficulty in accessing the segment; (3)land use, based on the surrounding areaimmediately 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 extentof erosion present. Quantitative measurementsat each segment included flow, depth, wettedwidth, velocity, and stream gradient.
Fish and herpetofauna were sampled duringthe summer index period using quantitative,double-pass electrofishing of the 75 m streamsegments. Blocking nets were placed at eachend of the segment, and one or more direct-current, backpack electrofishing units wereused to sample the entire segment usingdouble-pass depletion. All fish capturedduring each electrofishing pass were identi-fied, counted, weighed in aggregate, and up to100 individuals of each species were exam-ined for external anomalies such as lesionsand tumors. All gamefish captured were alsomeasured for length. Any amphibians, reptiles,freshwater molluscs, and submerged aquaticvegetation either in or near the stream segmentwere identified.
Data collected from each sample site wereused to develop statewide and basin-specificestimates of totals, means (or averages),proportions, and percentiles for the parametersof interest. The amount of variability (ormargin of error) associated with any estimateof a total, mean, proportion, or percentile wasdetermined by calculating a standard error, a
Technical Appendix
57
statistic that measures the reliability of anestimate. A standard error also provides astatistical basis for deciding if the observedchanges in any parameter of interest over timeor space are significantly different or simplydue to chance alone.
For all phases of the Survey, there was anongoing, documented program of qualityassurance/quality control (QA/QC). The QA/QC program used by the Survey allows forgeneration of data with known confidence.
Index of BioticIntegrityThe steps in developing Indices of BioticIntegrity (IBIs) were the same for both fishand benthic macroinvertebrates. Criteria forboth reference and degraded sites weredetermined based on water chemistry, physicalhabitat, and land use. Ecologically-relevantgeographic strata were determined usingcluster analysis and nonmetric multidimen-sional scaling. Candidate metrics were evalu-ated for 1) their ability to discriminate (basedon classification efficiency) between referenceand degraded sites, and 2) for redundancy. Thefinal suite of metrics used in the IBIs con-tained those ecologically significant metricswith the best classification efficiency. BothIBIs were validated using an independent dataset and overall classification efficiencies werecalculated.
The potential range of IBI scores was from 1.0to 5.0. Narrative ratings for stream qualitywere assigned as in the table below. In thisreport, good, fair, and poor ratings of streamquality were indicated by red, yellow, andgreen, respectively.
IBIs were not calculated for selected samplingsites. For instance, no fish IBIs were calcu-lated for those sites having upstream water-sheds less than 300 acres, since small, shallowstreams may naturally support few fishspecies. In these small streams the IBI mayindicate natural conditions rather than anthro-pogenic stresses. Benthic macroinvertebrateIBIs were not calculated for sites with smallsubsample sizes (i.e., less than 60 organismswhere no obvious impairment was present).Seventeen percent of all sites with both fishand benthic macroinvertebrate samples hadbenthic IBIs but no fish IBIs.
To provide a more integrated picture of overallstream health, fish and benthicmacroinvertebrate IBIs were combined (whereboth IBIs were available) into a CombinedBiotic Index (CBI). CBI scores were producedby calculating the mean IBI score for bothbenthic and fish IBIs if both were available. Ifboth were not available, one or the other IBIwas used alone for the CBI. The numberingand coloring scheme described above for theIBIs were used for the CBI.
WatershedsAlthough the Survey provides information ona major river basin scale, many readers maywant stream information based on otherwatershed designations. For example,Maryland�s Tributary Strategies divide thestate into 10 river basins (Figure A1), whilefor some readers, smaller watershed informa-tion may be desired (Figure A2). Table A1provides a cross reference for major riverbasins, Tributary Strategies Basins, andwatersheds.
Good (IBI score 4.0 - 5.0) Comparable to reference streams considered to beminimally impacted.
Fair (IBI score 3.0 - 3.9) Comparable to reference conditions, but some aspectsof biological integrity may not resemble the qualities ofminimally impacted streams.
Poor (IBI score 1.0 - 2.9) Significant to strong deviation from reference conditions,with many to most aspects of biological integrity notresembling the qualities of minimally - impacted streams.
Technical Appendix
Figure A1 (above) and A2 (below). Maryland�s 10 Tributary Strategies basins areshown in Figure A1. Figure A2 shows the 138 watersheds (in red) that are usuallymore familiar to most Maryland residents. The blue lines in both maps show theboundaries of the major river basins that are the reporting units in this report. SeeTable A1 on page 51 for a list of each watershed, its corresponding major riverbasin, and Tributary Strategies basin.
Technical Appendix
50
59
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Maryland BiologicalStream SurveyFor current information on the Survey, visitMaryland DNR�s World Wide Web homepageat http://www.dnr.state.md.us and wade onover to Bays and Streams. A detailed sum-mary of three years of Survey sampling iscontained in the report, State of the Streams:1995-1997 Maryland Biological StreamSurvey Results. Call Ann Smith at 1-(877)-620-8DNR (extension 8611) or (410) 260-8611 (email: [email protected]) for acopy of this or other Survey reports (expect acharge to cover printing and postage) or to addyour name to the mailing list for our newslet-ter, An Eye on Maryland Streams. Thenewsletter may also be found online at DNR�swebsite noted above.
If you would like more information about themethods used to sample Maryland streams andanalyze data, call Ann Smith at the abovenumber and ask for the MBSS SamplingManual (expect a charge to cover printing andpostage).
For more information on the Quality ofMaryland�s Streams...
Maryland Watershedand CitizenMonitoringOrganizations
For information on Maryland�s TributaryStrategies, call 1-(877)-620-8DNR (extension8710) or (410) 260-8710 or check out http://dnr.state.md.us/Bay/tribstrat. To contact otherwatershed organizations in Maryland, go tothe Alliance for the Chesapeake Bay�s websiteat http://www.acb-online.org. Also, theMaryland Water Monitoring Council works tofoster cooperation among groups involved inall types of water monitoring activities inMaryland. Learn more about the Council athttp://www.mgs.md.gov/mwmc/. For informa-tion on Maryland�s volunteer monitoringprograms, call the state Volunteer MonitoringCoordinator at (410) 260-8696 or email her [email protected] or visit the DNRwebsite.
Parris N. Glendening, GovernorKathleen Kennedy Townsend, Lt. Governor
Sarah J. Taylor-Rogers, Ph. D., SecretaryStanley K. Arthur, Deputy Secretary
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WE NEED YOUR HELP...We would like to know if From the Mountains to the Sea: the State of Maryland�s Freshwater Streamsprovides you with useful information and if you would like to receive future reports. The estimatedtime it takes to complete this survey is less than three minutes. Your response to the following ques-tions will help us meet your needs:
OMB Control Number: 2090-0019
Yes
No
Don
�tK
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2. Is this report easy to understand?
3. The contents of the report were useful to me.
4. Which part(s) of the report did you find the most useful or least useful?
a. Introduction
b. The State of Maryland�s Streams
c. The Future of Maryland�s Streams
d. It Will Take Teamwork
5. If information was provided using the Geographic Information Systems (GIS) data, would it be useful to you?
1. What best describes the function of your organization/responsibility?
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Public reporting burden for this collection of information is estimated to average three (3) minutes per response, including the time for reviewinginstructions, gathering information, and completing and reviewing the collection of information. Send comments on the agency�s need for thisinformation, the accuracy of the provided burden estimates, and any suggestions for reducing the burden, including the use of automated collectiontechniques to the Director, OEI, Collection Strategy Division, United States Environmental Protection Agency (Mail Code 2822), Ariel Rios Building,1200 Pennsylvania Avenue NW, Washington, DC, 20460; and to the Office of Information and Regulatory Affairs, Office of Management andBudget, 725 17th Street NW, Washington, DC, 20503, Attention: Desk Officer for EPA. Include the EPA ICR number and the OMB control numberin any correspondence.
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