pahs in urban waters

8/12/2019 PAHs in Urban Waters

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What are PAHs?

PAHs, or Polycyclic Aromatic Hydrocarbons,consist o hundreds o separate chemicals thatoccur together as mixtures. PAHs are naturallyoccurring and are concentrated by the burn-ing o ossil uels and the incomplete burningo carbon-containing materials (such as wood,tobacco, and coal). PAHs are a wide and variedgroup o compounds whose sources include tire

particles, leaking motor oil, vehicle exhaust,crumbling asphalt, atmospheric deposition,coal gasification, and parking lot sealants, aswell as sources inside the home (such as tobaccosmoke, wood fire smoke, grilling or char-ring meat). PAHs are also commonly ound inparticulate matter o air pollution. PAHs tendto adhere to suraces, attaching readily to sedi-ment particles and leading to elevated con-centrations in sediments. PAHs have complexchemical structures (see figure 1), so they donot break down easily and are persistent in theenvironment.

Why should we be concerned about PAHs?

Some PAHs are known to be toxic to aquaticanimals and humans. Generally, higher molecular

weight PAHs tend to be more stable, persist in theenvironment longer, are less water soluble, andare more toxic. Exposure to UV light can increasetoxicity o PAH compounds and increase toxicityto some aquatic species. (Garrett 2004)

Scientific studies have documented detri-mental impacts rom PAHs on aquatic organ-isms. Examples include:

In Austin, exas biological studies revealed

a loss o species and decreased number oorganisms in streams with PAHs present(Van Metre 2005)

Polycyclic Aromatic Hydrocarbons (PAHs)

in Urban Waters

Purpose of this document

Recent studies by the US Geological Survey (USGS) and several universities indicate that PAHs arean important emerging contaminant in urban waterways, including the rapidly growing metroareas of North Carolina. This document offers an overview of recent studies of potential sourcesfor PAHs in urban waterways and provides information on management strategies for reducingthe risks of PAH impacts on aquatic ecosystems.

Figure 1. The chemical structure of Benzo[a]-

pyrene, a carcinogenic PAH.


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In Puget Sound, WashingtonsAmbient Monitoring Program(WA DFW) ound PAHs wereassociated with: Liver lesions and tumors in fish, Liver problems leading to repro-

ductive impairment,

Malormations in fish embryosand embryonic cardiacdysunction,

Reduction in aquatic plants (eel-grass) that provide fish habitat.

Benzo(a)pyrene was lethal to newtlarvae at low levels (50 parts perbillion) (Fernandez and Lharidon1994)

A 2006 study showed develop-mental delays and deormitiesin amphibians with exposure to

coal tar pavement sealants (whichcontain PAHs), with larger levelso sealant causing greater devel-opmental problems and death.(Bryer 2006)

Brown bullhead catfish andEnglish sole have been docu-mented as among the moresensitive bottom-dwelling fish tothe carcinogenic effects o PAHs(Garrett 2004).

Crustaceans and fish metabolize

PAH compounds more efficientlythan do bivalve species suchas mussels, clams, and oysters,which readily accumulate PAHs(Garrett 2004).

Interactions between aquaticorganisms and PAHs in sedimentare complex, depending on manyactors includingbut not limitedtosensitivity o species, stageo development, bioavailability oPAHs, and exposure to sunlight(Garrett 2004).

Te most significant effect oPAH toxicity to humans is cancer.Increased incidences o lung, skin,and bladder cancers are associatedwith occupational exposure to PAHs(USDHHS 2009). Other non-cancereffects are not well understood,though they may include adverseeffects on reproduction, development,

their tendency to attach to particlesrather than dissolve in water. USEPAhas a maximum contaminant level(MCL) or PAH in drinking water o0.2 ppb o drinking water. Humanhealth risks rom consuming fishare thought to be low because PAHs

do not readily bioaccumulate withinvertebrates. Bivalve mollusks read-ily accumulate PAHs in their tissues,however. (Garrett 2004). Te U.S.Food and Drug Administration (FDA)has not established standards govern-ing the PAH content o oodstuffs(USDHHS 2009), with the excep-tion o issuing levels o concerns orPAHs in fish and shellfish ollowingthe Deepwater Horizon oil spill. TeEuropean Union has set a maximum

allowable level o benzo(a)pyrene orbivalve mollusks on the market (EUCommission 2006).

How do PAHs get into streams,lakes, estuaries, and the ocean?

PAHs enter water bodies throughatmospheric deposition and directreleases o substances through petro-leum spills and use, municipal waste-water treatment plants, industrial

and immunity. PAHs generally havea low degree o acute toxicity tohumans, meaning harmul effectsthrough a single or short-termexposure are minimal. Mammalsabsorb PAHs through inhalation,contact with skin, and ingestion (EPA

Ecological oxicity). Recent researchby USGS raises concerns about expo-sure o children through inhalationand ingestion o house dust con-taminated by PAHs that have abradedrom nearby parking lots sealed withcoal tar sealant (Mahler 2010).TeInternational Agency or Research onCancer (IARC) classifies two PAHsas probable human carcinogens andthree as possible human carcinogens.Te US EPA classifies seven PAHs as

probable human carcinogens, whilethe state o Caliornia classifies 25PAHs as carcinogenic PAHs (cPAHs).Te IARC and EPA both classiybenzo(a)pyrene and benz(a)anthra-cene as probable human carcinogens.Benzo(a)pyrene is ofen used as anenvironmental indicator or PAHs.

PAHs in streams and lakes arethought to rarely pose a human healthrisk via drinking water because o

Figure 2. Bivalves, including oysters, readily accumulate PAHs in their tissues.


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Polycyclic Aromatic Hydrocarbons (PAHs) in Urban Waters

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discharges, stormwater runoff, landfillleachate, and surace runoff. Manystudies have been conducted recentlyregarding runoff sources o PAHs.Rainall runs off parking lot and roadsuraces, transporting PAHs thatoriginate rom tire particles, leaking

motor oil, vehicle exhaust, crumblingasphalt, atmospheric deposition, coalgasification, and parking lot seal-ants. PAHs attach readily to sedimentparticles, leading to high concentra-tions in bottom sediments o waterbodies. A literature review on tirewear particles in the environmentindicates that the high aromatic (HA)oils generally used in tires containPAHs. Zinc, PAHs, and a suite oother organic compounds (including

phthalates, benzothiazole derivatives,phenolic derivatives, and atty acids)ound in tires are noted to likely causetoxicity in aquatic organisms. Becauseo this toxicity, the European Unionhas banned sales o tires that containHA oils. Tis is estimated to reduceuture PAH emissions rom tires by98 percent. (Wik & Goran 2009) It isunclear whether tire manuacturerswill continue to sell tires containingHA oils in the United States.

Coal tar-based sealants

Research rom the USGS in the Cityo Austin, exas (Van Metre et al2005), nine other cities (Van Metreet al 2009)), and rom the Universityo New Hampshire (Mahler et al2012) indicates that coal tar-basedsealants (also called sealcoats) onparking lots likely contribute sig-nificant amounts o PAHs to water-ways via stormwater runoff. Tesesealants (CS) are made o coal tar,a product created during the cok-ing o coal. Tis type o sealant andanother sealant made rom asphaltare used to prevent damage to asphaltsuraces. Friction rom automobiletires causes the sealcoat to flake off.Tese flakes are then scrubbed romthe surace during a rain event andinto storm-drain networks, and thenflow into lakes and streams. In the

Austin study, parking lots with coaltar sealcoat yielded an average PAHconcentration o 3,500 mg/kg onparticles in runoff, 65 times morethan rom unsealed lots in simulatedrain events. Te average concentra-tion o PAHs in particles washed offasphalt-based sealants was 620 mg/kg,

about 10 times higher than the aver-age concentration rom the unsealedparking lots. Te other sources oPAHs previously mentioned, besidessealants, can account or the PAHconcentrations ound washing off theunsealed parking lots (Van Metre2005). A recent UNH study comparedrunoff rom lots they sealed with bothtypes o sealants to an unsealed lot.Tey ound both types o sealcoat ledto a rapid increase in PAH concentra-tions in the initial runoffup to 5,000parts per billion (ppb), compared to10 ppb released rom the unsealedlot. Concentrations decreased aferseveral rainstorms. Te PAH concen-trations in the sediments immediatelydownstream o the coal tar sealedlot increased by nearly two orders omagnitude within the first year (14).Te Pavement Coating echnologyCouncil maintains that improper

curing o the test plots at UNH con-tributed to the high concentrationso PAHs ound in runoff (LeHuray2009). Te results o analyzing sourceso PAHs in sediment cores rom 40lakes across the U.S. has led someUSGS researchers to conclude thatcoal tar sealcoat likely is the primary

cause o upward trends in PAHs inresponse to urban sprawl in much othe United States. (Van Metre 2010)

Attributing sources of PAHsto land uses

Determining the sources o PAHs instreams is a complex process and isusually done by evaluating the ratioso individual compounds oundin stream sediment. USGS is cur-rently conducting research in NorthCarolina to examine PAH concentra-tions in bridge deck runoff. Researchon metals and PAHs in Santa Monica,Caliornia, ound that both com-mercial and industrial land uses androads provided higher concentrationso both metals and PAHs than single-amily residential land uses (Lau &Strenstrom 2005). A study o the rela-tive importance o individual sourceareas in contributing to contaminants

Figure 3. Sealant is applied to a parking lot.

United States Geological Survey


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echo studies rom around theworld (Garrett 2004).

Levels o PAHs have been indi-cated by NCDWQ as the leadimpairment o Burnt MillCreek, an urban stream inWilmington, N.C. A subsequent

UNC-Wilmington/NC StateUniversity research project oundhigh levels o PAHs through-out the creek at six sites or ouryearly sampling events. Zinclevels, which can be used as indi-cators o tire-wear particles, were

in an urban watershed in Marquette,Michigan, ound parking lots to bea major contributor (~64 percent) oPAH compounds (Steuer et al 1997).Te USGS study o bridge decks maybe the first North Carolina studyevaluating land-use contributions

to PAH concentrations in water-ways. Future research in N.C. couldseek to attribute sources o PAHsto land uses, including commercialand industrial land uses, roads, andparking lots. Estimating PAHs romvarious land uses could be calculatedusing methods used in the Marquette,Michigan, study.

How do PAHs affect streamsin North Carolina?

Te North Carolina Division o WaterQuality (NCDWQ) does not moni-tor the presence o PAHs in streams.Laboratory analysis or PAHs is muchmore expensive than or commonlymeasured pollutants like nutrientsand bacteria, and North Carolina hasno official standard or PAHs. Specialstudies do sometimes include PAHanalysis, such as:

Te USGS National Water QualityAssessment ound a strong cor-relation between PAHs and urbanintensity across the country,including 30 watersheds o theRaleigh-Durham metro area. Tehighest concentrations o PAHs insediments at the bottom o waterbodies were ound in watershedswith increasing development andmotor vehicle traffic. Tese results

At what concentration do

PAHs affect in-stream aquaticorganisms?

The sediment quality guideline,

known as the Probable EffectConcentration (PEC), representsthe concentration of a contami-

nant in bed sediment expectedto adversely affect bottom-

dwelling organisms. The PECfor PAHs is 22.8 mg/kg.

Figure 4. Burnt Mill Creek is an urban stream in NC that is impaired by PAHs.

Figure 5. This bioretention cell reduced PAHs in runoff owing through it.


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low at these same sampling sites,indicating that tire-wear particlesrom parking lots may be ruledout as major contributors to thiswatersheds PAH toxicity prob-lems. (Perrin et al 2008)

Reducing risk of PAH contaminationfrom stormwater runoff

Use asphalt sealants or latex modi-fied asphalt sealants if sealing anasphalt surface is necessary. Asphaltor latex modified asphalt sealantscontain PAH concentrations o about5 percent, whereas coal tar based-sealants contain between 20 to 35percent PAHs. Homeowners shouldread and ollow directions closely orapplying and curing the sealant, or

consider hiring a trained proessional.Industry proessionals note that coaltar-based sealants perorm better thanasphalt sealants at protecting parkinglots rom petroleum and UV degrada-tion and wear, and they are ocusingresearch and development on creatinghigher-perorming asphalt sealants(WECO 2009).

A number o national home-improvement and hardware storeshave discontinued coal tar-based seal-

ants (Hogue 2007), so homeownerswho purchase sealant at these storesare using asphalt or latex modifiedasphalt sealants. Tat said, coal tar-based sealants are still readily avail-able or purchase online and throughwholesale and commercial suppliers,and they are produced and used inNorth Carolina (WECO 2009).

Intercept and manage stormwa-ter runoff from all parking lots androads. PAH compounds can beremoved rom aquatic systems ortransormed to new compounds byvolatilization (o low molecularweight PAHs), photo oxidation, andbiodegradation (Garrett 2004).Installing bioretention cells (alsocalled rain gardens) to treat parkinglot runoff reduces PAHs in stormwa-ter, likely through biodegradation.An NC State study in Wilmington,N.C., ound a reduction in the

concentration o PAHs rom parkinglot runoff afer treatment by a veg-etated bioretention cell (Wright et al2009). A University o Marylandstudy indicates that a shal low biore-tention cell design is adequate orremoving PAHs, with mitigationocused on the top surace layer nearthe inlet where sediment accumula-

tion occurs. PAHs were ound to bedegraded through indirect plantprocessing o microbial-soil-rootinteractions with the rhizosphere(the area o soil 1 mm rom the plantroot). (Diblasi, et al 2009). SincePAHs are ofen sediment-bound,stormwater practices that reducesediment (such as bioretention,stormwater wetlands, wet ponds,swales, and filter strips) may beimportant or reducing PAH concen-trations. Some proprietary stormwa-ter management devices, such as inletfiltration devices, are marketed asreducing organic toxins, includingPAHs. Regular maintenance o theseand al l stormwater managementdevices is integral or continuedpollutant removal (see AG-588-7 orurther discussion on maintenance).Proper disposal o contaminatedsediment is a concern.

Recommendations or disposing osediments rom BMP maintenanceare included in the NCDENRStormwater Best ManagementPractice Manual.

Create parking lots with surfacesother than asphalt, such as concreteor permeable pavement. Te uprontcosts or installing concrete are higher

than those or installing asphalt park-ing lots. Long-term maintenance islikely lower, however, since concreteparking lots do not require sealantsand have a longer liespan. Te lightersurace o concrete also provides a ben-efit o reducing the urban heat islandeffect by absorbing less solar energythan darker suraces (EPA 2008).Pervious pavement, including inter-locking pavers and permeable concreteare alternatives to concrete and asphaltthat reduce stormwater runoff and pol-lution (see AG-588-14). Although per-vious pavement is the most expensiveo the paving options when consider-ing only construction cost, regulatorycredit rom NCDENR or reducingimperviousness and attenuating peakrunoff with appropriate design can off-set the cost. Tis may allow permeablepavement to replace or reduce the sizeo other stormwater practices.

Figure 6. A parking lot with interlocking pavers in Swansboro, N.C.


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Summary

PAHS have been identified by USGSas an important emerging contami-nant in the waterways o growingmetropolitan areas o the UnitedStates, including those o NorthCarolina. Negative impacts romPAHs in waters have been well docu-mented in fish, amphibians, bivalves,and benthic macro-invertebrates.

Human-health impacts rom drink-ing water and short-term contact withcontaminated waters are thought tobe minimal, though consumption ocontaminated bivalves is a concern.Tere are many potential sourceso PAHs to urban waters, though agrowing body o research has high-lighted the use o coal tar based park-ing lot sealant as a major contributor.Strategies or reducing the risks oPAHs to aquatic ecosystems includeeliminating the use o coal tar-basedsealants on parking lots, interceptingand managing runoff rom parkinglots and roads, and creating parkinglots with materials that dont requiresealing such as concrete or permeablepavement.

Acknowledgments

Funding or this act sheet wasprovided by the NC Clean Water

Management rust Fund and the USEnvironmental Protection Agency,CWA Section 319.

Early versions o the act sheetwere reviewed by Sharon Fitzgerald,U.S. Geological Service, and DavidMayes and Jennier Butler, City oWilmington Stormwater ServicesDivision.

Peer review o this act sheet

was conducted by Bill Hunt, P.E.,Ph.D., associate proessor, and MikeBurchell, P.E., Ph.D., assistant proes-sor, Department o Biological andAgricultural Engineering, NorthCarolina State University; and MitchRenkow, Ph.D., proessor, Departmento Agricultural and ResourceEconomics, North Carolina StateUniversity.

References

Ahrens, M.; C.Depree; Olsen. G.Environmental orensics: crackingthe case o the contaminated streams.2007. Water & Atmosphere 15(1).Online at www.niwa.co.nz.

Bryant, W.L., S.L. Goodbred,.L. Leiker, L. Inouye, B.. Johnson.2007. Use o Chemical Analysis andAssays o Semipermeable MembraneDevices Extracts to Assess theResponses o Bioavailable Organic

Pollutants in Streams to Urbanizationin Six Metropolitan Areas o theUnited States. U.S. Department othe Interior, U.S. Geological Survey.Scientific Investigations Report2007-5113.

Bryer, P.J., J.N. Elliot, J.N., E.J.

Willingham. 2006. Te effects o coaltar-based pavement sealer on amphib-ian development and metamorpho-sis. Ecotoxicology, 15. New York:Springer Science+Business Media.

European Union. CommissionRegulation No. 1881/2006 o 19December 2006. (2006). Settingmaximum levels or certain contami-nants in oodstuffs.

DiBlasi, C.J., H. Li, A.P.Davis, U. Ghosh. 2009. Removal

and Fate o Polycyclic AromaticHydrocarbon Pollutants in an UrbanStormwater Bioretention Facility.Environmental Science & echnology,43(2) Washington, D.C.: AmericanChemical Society Publications.

Environmental ProtectionAgency. Region 5 Superund.Ecological oxicity Inormation.Online at: http://www.epa.gov/R5Super/ecology/html/toxprofiles.htm#pahs

Fernandez, M. , J. Lharidon.1994. Effects o light on the cytotox-icity and Genotoxicity o Benzo(a)pyrene and an oil refinery effluentin the newt. Environmental andMolecular Mutagenesis. Volume 24Issue 2. Wiley-Blackwell.

Garrett, C.L. 2004. Prioritysubstances o interest in the GeorgiaBasin: profiles and backgroundinormation on current toxics issues:Report o the Canadian oxics WorkGroup. GBAP Publication no. EC/GB/04/79. Online at: [email protected]

Hogue, C. 2007. Dustup OverPavement Coatings. Chemical& Engineering News. Volume 85,Number 7. pp. 61-66. Washington,D.C.: American Chemistry SocietyPublications.

Lau, S-L. , M.K.Stenstrom, 2005.Metals and PAHs adsorbed to street

Figure 7. A permeable pavement lot in Wilmington, N.C.


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particles. Water Research. Volume39, Issue 17, October, 4083-4092.London: IWA Publishing.

LeHuray, Anne P. 2009. PavementCoatings echnology Council. Letterto author. October 20, 2009.

MacDonald, D.D., C.G. Ingersoll,

.A. Berger. 2000. Developmentand evaluation o consensus-basedsediment quality guidelines orreshwater ecosystems. Archiveso Environmental Contaminationand oxicology. 39:20-31. New York:Springer Science+Business Media.

Mahler, B.J., P.C.Van Meter, J..Wilson, M. Musgrove, .L. Burbank,.E. Ennis, .J. Bashara. Coal tar-based parking lot sealcoat: An unrec-ognized source o PAH to settled

house dust. Environmental Scienceand echnology. 2010. 44, Pp 894-900. Washington, D.C.: AmericanChemistry Society Publications.

Mahler, B.J.; P.C. Van Metre, .J.Bashara, D.A. Johns. 2005. Parkinglot sealcoat- An unrecognized sourceo urban PAHs. EnvironmentalScience and echnology, V. 39,p. 5560-5565. Washington, D.C.:American Chemistry SocietyPublications.

North Carolina Departmento Environmental and NaturalResources. 2007. Stormwater BestManagement Practices Manual.Raleigh, NC: Division o WaterQuality. http://portal.ncdenr.org/web/wq/ws/su/bmp-manual

North Carolina Departmento Environmental and NaturalResources. 2004. Assessment Report:Biological Impairment in the BurntMill Creek Watershed. Divisiono Water Quality, CollaborativeAssessment o Watersheds andStreams (CAWS) Project.

WECO Focus group. ParkingLots and Water: A ocus group orproessionals in the business obuilding and/or sealing parking lots.August 17, 2009. Wilmington, NC.Sponsored by NC State UniversityCooperative Extension and City oWilmington.

Perrin, C.A.; Wright, J.; W.F.Hunt, P.G. Beggs, M. Mallin, M.Burchell. 2008. Restoring the BurntMill Creek Watershed throughStormwater Management andCommunity Development. Final EPA319 Report to NC Division o Water

Quality. Online www.ncsu.edu/WECO/burntmillRichardson DC. 2006. Parking

lot sealants: on the trail o urbanPAHs. Stormwater, Te Journal orSurace Water Quality Proessionals,7 (4). Santa Barbara, CA: ForesterMedia Inc.

SeaGrant New Hampshire.Pavement Sealcoat a Source o oxinsin Stormwater Runoff. Online at:http://www.seagrant.unh.edu/news-

sealcoat.htmSteuer, J.,W. Selbig, N.

Hornewer, J. Prey. 1997 . Sources oContamination in an Urban Basin inMarquette, Michigan, and an Analysiso Concentrations, Loads, and DataQuality. U.S. Geological SurveyWater Resources InvestigationsReport 97-4242; U.S. GeologicalSurvey: Denver, CO,.

U.S. Department o Healthand Human Services, Agency or

oxic Substances and DiseaseRegistry (ASDR). July 1,2009.oxicity o Polycyclic AromaticHydrocarbons (PAHs). Case Studiesin Environmental Medicine. Online athttp://www.atsdr.cdc.gov/csem/pah/pah_where-ound.html

U.S. Department o Health andHuman Services, Public HealthService. Agency or oxic Substancesand Disease Registry (ASDR)oxFAQ or Polycyclic AromaticHydrocarbons (PAHs). Online at:http://www.atsdr.cdc.gov/tacts69.html

Food and Drug Agency. Protocolor Interpretation and Use o Sensoryesting and Analytical ChemistryResults or Re-Opening Oil-ImpactedAreas Closed to Seaood HarvestingDue to Te Deepwater Horizon OilSpill. June 2010, Updated November2010.

Van Metre, P.C., B.J. Mahler. 2010Contribution o PAHs rom coaltarpavement sealcoat and other sourcesto 40 U.S. lakes. Science o the otalEnvironment 409 (2010) 334344.Elsevier publications.

Van Metre, P.C, B.J. Mahler, J..

Wilson. 2009. PAHs Underoot:Contaminated Dust rom Coal tarSealcoated Pavement is Widespreadin the United States. EnvironmentalScience and echnology 43 (1), pp2025. Washington, D.C.: AmericanChemistry Society Publications.

Van Metre, P.C, B.J. Mahler,M. Scoggins, P.A. Hamilton. 2005.Parking lot sealcoat- A major sourceo PAHs in urban and suburbanenvironments: U.S. Geological Survey

Fact Sheet 2005-3147, 6 pp.Washington Department o Fish

and Wildlie, Puget Sound AmbientMonitoring Program. Online at http://www.wdw.wa.gov/fish/psamp/

Wik, A.,G. Dave. January 2009.Occurrence and effects o tire wearparticles in the environment A criti-cal review and an initial risk assess-ment. Environmental Pollution,Volume 157, Issue 1. Pages 1-11.Elsevier publications.

Wright, J.D.; Hunt,W.F.;Burchell,M.R.; Perrin, C.A.;McCoy, E.R.Implementation and perormance ostormwater best management prac-tice retrofits in Wilmington, NC.Proceedings o World Environmentaland Water Resources Congress 2009:Great Rivers 2009;342():5293-530.Kansas City, MO.

Environmental ProtectionAgency. 2008. Reducing Heath Islands:Compendium o Strategies CoolPavements. Available at: www.epa.gov/heatisld/mitigation/pavements.htm


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NC STATE UNIVERSITY

Prepared by

Christy Perrin, Extension Associate,

Program Manager of Watershed Education for Communities and Officials

Department of Agricultural and Resource Economics

North Carolina State University

Published by

NORTH CAROLINA COOPERATIVE EXTENSION SERVICE

Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina

A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, nationa

origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North

Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

10/12VB/BW 13-CALS-3429 AG-588-25

pahs in urban waters

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