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TM‐8 Page 1
TM‐8: Watershed Management and Protection
1.0 Introduction Anapprovedsourcewaterassessmentandprotectionplan(SWAP)providesmultiplebenefitstoboththedrinkingwaterutilityandthecommunityingeneral.Thoughchangesinwaterqualityinawatershedaretypicallyslow,itmaybepossibletoimprovewaterqualitythroughexecutionofmanagementandeducationalstrategies.Sourcewaterqualitydirectlyimpactstreatmentprocessrequirements,regulatorycomplianceandtreatmentcosts.Therefore,improvementsinsourcewaterqualityarebeneficialtothedrinkingwatersystemandcanalsoprovideaestheticimprovementsforcommunitiesalonglakesandDetroitRiver.
ThistechnicalmemorandumdiscussestheUnitedStatesEnvironmentalProtectionAgency(EPA)andMichiganDepartmentofEnvironmentalQuality(MDEQ)requirementsandrecommendationsregardingsourcewaterassessmentandprotection.TheSourceWaterAssessmentProgram(SWAP)andSurfaceWaterIntakeProtectionProgram(SWIPP)aredescribedandcurrentDWSDreportsassessed.RulesspecifictotheGreatLakesarepresented.SinceportionsofthesourcewaterareasandoneoftheDWSDintakesareinCanadianwaters,theOntariosourcewaterprotectionprogramisreviewed.Theregulatorysectionconcludeswithalookatpotentialfutureregulations.
Sourcewaterqualityisdiscussedspecificallyasitmaybeimpactedbyclimatechange,bytheintroductionofzebramusselsandbyspills.GiventhattheLakeHurontoLakeSt.ClairtoDetroitRiverisamajorshippingchannelandshorelinemanufacturinglocation,detailsregardingspillsarediscussed.ThistechnicalmemorandumdiscussestheHurontoErieWaterQualityMonitoringSystem.Thisisamulti‐communitynetworkofwaterqualitymonitorsdevelopedspecificallytodetectspillsandothercontaminationevents.Finalrecommendationsarepresentedforimprovementstotheoverallsourcewaterassessmentandprotectionprogram.
2.0 Source Water Assessment Program (SWAP) & Surface Water Intake Protection Program (SWIPP)
TheMichiganDepartmentofNaturalResourcesandtheEnvironment(MDNRE,nowtheMDEQ)completedaSourceWaterAssessmentProgram(SWAP)asrequiredbythe1996reauthorizationoftheEPASafeDrinkingWaterAct(SDWA).TheseSDWAamendmentsrequiredthestatesto:
Delineatethesourcewaterassessmentarea
Conductaninventoryofpotentialsourcesofcontamination,includingspillassessment
Determinethesusceptibilityofthewatersupplytocontamination
Providepublicinformation;includingspecificlanguagethatmustbeincludedintheConsumerConfidenceReport
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AllDWSDintakeshaveapprovedSWAPsbytheMDEQin2004.DWSDobtainswaterfromthreesources:
LakeHuronwhichprovideswatertotheLakeHuronWaterTreatmentPlant(WTP)
BelleIsleintheDetroitRiverwhichprovideswatertoWaterWorksParkWTP,SpringwellsWTPandNortheastWTP
FightingIslandintheDetroitRiverwhichprovideswatertoSouthwestWTP
TheSurfaceWaterIntakeProtectionProgram(SWIPP)isprogramdevelopedbytheMDEQtoprovideguidancetocommunitiesaftertheSWAPhasbeencompleted.ASWIPPincludesthesamesevenelementsastheWellheadProjectionProgram:
Definitionofrolesanddutiesofgovernmentunitsandwatersupplyagencies
Designationofasourcewaterprotectionareaforeachwatersupplysource(basedontheMDEQ’sdefinedsourcewaterarea)
Identificationofpotentialcontaminantsources
Implementationofmanagementapproachesforprotectionofsourcewater,includingbutnotlimitedtoeducationalandregulatoryapproaches
Creationofcontingencyplansforpublicwatersupplysourcesincludingthelocationofalternatedrinkingwatersources(ContingencyplansarediscussedinTMNo.13EmergencyResponsePlan)
Propersitingofnewwatersourcestominimizepotentialcontamination
Encouragementofpublicparticipation
DWSDhasnotcompletednorobtainedanapprovedSWIPPforanyoftheintakes.
2.1 Existing SWAPs
TheUSGS(UnitedStatesGeologicalSurvey),theMDEQandDWSDcompletedtheSWAPrequirementsfortheDWSDsystemin1999.SWAPswereapprovedbyMDEQin2004.ThecompletedSWAPsincludetheregulatoryrequiredinformationaswellassectionson:
RegulatoryReview
BackgroundontheDetroitwatersystem
Sourcewatergeologyandhydrology
Rawwaterqualityhistory
References
Glossary
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Rawsourceswereratedforsensitivityandsusceptibility.Sensitivityisanindicationofthenaturalprotectionaffordedthesourcewaterbyitsnaturalsetting.Susceptibilityisbasedonfactorswithinthesourcewaterprotectionareathatmayposearisktothewatersupply.Thesusceptibilityratingisbasedonfourfactors:
Thepresenceofpotentialcontaminantsourcesfromthecontaminantinventoryandthelikelihoodthatcontaminantswillbereleasedfromthosecontaminationsources
Thephysicalintegrityoftheintake
Thesensitivityofthenaturalsettings
Thepresenceofexistingorlikelycontaminationofthesourcewater
TheEPA(2006)notesthattherearemultiplemethodsfordevelopingasourcewaterprotectionarea.Theorderofincreasingaccuracyandsophisticationis:
Arbitraryfixedradius
Calculatedfixedradius
Fixedvariableshapes
Analyticalmethods(suchastheuniformflowequation)
Hydrogeologicmapping
Numericalfloworflow‐and‐transportcomputermodels
Withinthesourcewaterprotectionarea,asubcategoryknownastheCriticalAssessmentZone(CAZ)isdetermined.TheCAZisthe“areafromtheintakestructuretotheshorelineandinland”.Theareaincludesatriangularwatersurfaceandlandareaencompassedbyanarcfromtheendpointoftheshorelinedistanceoneithersiteoftheonshoreintakepielocation”(MDEQ,1999).However,intheanalysisoftheCAZfortheDWSDintakes,theMDEQhastakenasimplifiedapproachwherebytheCAZisbasedonacombinationofthedistancefromtheshoretotheintakeandthewaterdepthresultinginCAZsof1,000or2,000or3,000feet.
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2.1.1 Lake Huron Intake
TheLakeHuronIntakeprovideswatertotheLakeHuronWTP.Thecriticalassessmentzone(CAZ)isshowninFigure2‐1.Forthisintake,theMDEQcalculatedtheCAZas1,000feetfromtheintake.
Figure2‐1:CriticalAssessmentZone,LakeHuronWaterIntake(SWAP,2004)Thepointandnon‐pointcontaminantsourcelocationsareshowninFigures2‐2and2‐3.AsummaryofthecontaminantsisprovidedinTable2‐1.Theassessmentidentifiesthefollowingpotentialcontaminants:
40listedsources,includingsolidwastesites,industrialfacilities,toxicreleaseinventoryandnationalpriorylistsites;19oftheseareinthesusceptiblearea
Urbanandagriculturalrunoff
Shipping
Themajorpotentialsourceofcontaminationwasshipping.NotethatCanadianlandandwateruseswerenotconsideredanimpactonthisintake.
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Figure2‐2:PotentialPoint‐SourceContaminantSources,LakeHuronIntakeSourceWaterProtectionArea(SWAP,2004)
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Figure2‐3:PotentialNon‐Point‐SourceContaminantSources&SoilPermeability,LakeHuronIntakeSourceWaterProtectionArea(SWAP,2004)
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Table 2‐1: Summary of Contaminant Sources for Lake Huron Intake (SWAP, 2004)
Type of Potential Contaminant Source
Number of Potential
Contaminant Sources
PCS within the Susceptible Area and
the CAZ Hazardous or Solid Waste Site 22 10 Industrial Facilities Discharge Site 10 6 National Priority List Sites 0 0 Permit Compliance System 5 2 Toxic Release Inventory 3 1 Canadian Wastewater Treatment Facilities 0 0 National Pollutant Release Inventory 0 0
ThisLakeHuronsourcewaterwasratedasmoderatesensitivityandmoderatelylowsusceptibilitybasedonthelimitednumberofpotentialcontaminantsources.
2.1.2 Fighting Island Intake
TheFightingIslandIntakeprovideswatertotheSouthwestWTP.TheCAZisshowninFigure2‐4.TheCAZforthisintakeextends2,000feet.Thepointandnon‐pointcontaminantsourcelocationsareshowninFigures2‐5and2‐6.
Figure2‐4:CriticalAssessmentZone,FightingIslandWaterIntake(SWAP,2004)