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Section 2.5 Hydrology and Water Quality
ThissectiondescribesthehydrologyandwaterqualityconditionsintheCountyandtheregulatoryframeworkapplicabletohydrologyandwaterquality.Italsoassessesthepotentialimpactsonhydrologyandsurfaceandgroundwaterqualitythatcouldresultfromprojectimplementation,andpresentsmitigationmeasuresthatwouldreducepotentiallysignificantimpacts.
Waterresourcescanbeclassifiedintotwocategories:(1)surfacewater,whichcollectsinstreams,rivers,lakes,andreservoirs;and(2)groundwater,whichresidesinsubsurfaceaquifers.Thissectiondealswithsurfacewater.GroundwaterresourcesarediscussedinSection2.8,WaterSupplyandGroundwater.Topicsrelatedtofloods,levees,ordams,andseiche,tsunami,ormudflowarediscussedinChapter3,EnvironmentalEffectsFoundNottobeSignificant.
2.5.1 Existing Conditions
2.5.1.1 Surface Water Hydrology
SurfacewaterbodiesintheCounty(e.g.,estuaries,lagoons,bays,lakes,reservoirs,rivers,andcreeks)capturetheflowoftheregion’swaterrunoff,oftencombiningnaturalrunoffwithimportedwater.Manyofthesewaterbodiessupportnaturalhabitatandrecreationalareas,andserveasstoragereservoirsfortheCounty’swatersupply.
TheSanDiegoregionisdividedintotwohydrologicbasins(theSouthCoastBasinandtheColoradoRiverBasin)bythenorthwest‐trendingPeninsularRange.TheCountyisdividedintotwohydrologicregions:(1)theSanDiegoHydrologicRegion,whichdrainsinawesterlydirectiontowardthePacificOceanandencompassesmostoftheCounty,partsofsouthwesternRiversideCounty,andsouthwesternOrangeCounty;and(2)theColoradoHydrologicRegion,whichdrainsinaneasterlydirectiontowardthedesertandColoradoRiverbasin.
Watershedsareareasintowhichsurfacerunoff,streams,creeks,andriversdrain.WithintheSanDiegoHydrologicRegion,theSouthCoastBasinsupports11majorwatersheds(orhydrologicunits)andisgovernedbytheSanDiegoRegionalWaterQualityControlBoard(RWQCB)(Region9).TheCarlsbad,SanDieguito,Penasquitos,SanDiego,PuebloSanDiego,Sweetwater,andOtaywatershedsarelocatedentirelywithintheSanDiegoregion.PortionsoftheSanJuanandSantaMargaritawatershedsaresharedwithOrangeandRiversideCounties,andtheTijuanawatershedwithMexico(SanDiegoAssociationofGovernments2015).WithintheColoradoHydrologicRegion,theColoradoRiverBasinsupportsportionsoffivewatershedsandisgovernedbytheColoradoRWQCB(Region7).TheAnza‐Borrego,Clark,Whitewater,WestSalton,andImperialwatershedsareintheeasternpartoftheCounty.ThesewatershedsareshownonFigure2.5‐1.
Fromnorthtosouth,the13principalstreamsystemsincludeAlisoCreek,SanJuanCreek,SanMateoCreek,SanOnofreCreek,SantaMargaritaRiver,SanLuisReyRiver,SanMarcosCreek,EscondidoCreek,SanDieguitoRiver,SanDiegoRiver,SweetwaterRiver,OtayRiver,andtheTijuanaRiver(SanDiegoRWQCB2011).MajorlakesandlagoonsincludeLakeO’Neil,SantaMargaritaLagoon,LakeHenshaw,BuenaVistaLagoon,AquaHediondaLagoon,BatiquitosLagoon,LakeWohlford,SanElijoLagoon,LakeSutherland,LakeHodges,SanDieguitoLagoon,LosPenasquitosLagoon,LakeJennings,
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LakeMurray,PaloVerdeLake,MorenaLake,andBarrettLake(CountyofSanDiego2007d).Streamsystemsandtheirreceivingwaters(lakes,bays,lagoons,andocean)supportavarietyofbeneficialusesthataredesignatedintheSanDiegoRegionBasinPlan.Beneficialusesaredefinedasthosewaterusesnecessaryforthesurvivalandwell‐beingofpeople,plants,andwildlife(SanDiegoRWQCB1994).Theseusesincludecleanandavailabledrinkingwater;agricultural,commercial,industrial,recreational,residential,andmilitaryuses;andwildlifeandhabitatuses.
Mostoftheregion’sstreamshaveperennialandephemeralsegmentsduetotheseasonalnatureofrainfallandtherelativelylowyearlyrainfall,orduetoeffectsfromdamsorotherhuman‐madeblockages.Surfacewaterimpoundmentscaptureflowfromnearlyalltheregion’smajorstreams,andrunofffromtheCounty’swatershedssupplies25reservoirswithacombinedcapacityofabout747,000acre‐feet(SanDiegoCountyWaterAuthority2015;SanDiegoRWQCB2011).Localrainrunoffintothesereservoirscontributestothewatersupplyfortheregion.ThereservoirsalsostorewaterimportedfromtheColoradoRiverandnorthernCalifornia.AsubstantialamountofthewaterdeliveredtohomesandbusinessesintheCity’sserviceareaiswaterthathasbeenimpoundedinthereservoirs.CountyreservoirsareshownonFigure2.5‐2.
2.5.1.2 Surface Water Quality
SeveralwaterbodysegmentsinSanDiegoCountyareonthefederalCleanWaterAct(CWA)Section303(d)listforimpairedwaterquality(seeSection2.5.2.1,FederalRegulations),andanycontributionofsubstantialadditionalpollutantsmayfurtherimpairthereceivingwaterbody.Atotalof72inlandsurfacewaterbodiesarecurrentlydesignatedasnotattainingapplicablewaterqualityobjectiveswithintheSanDiegoHydrologicRegion(SanDiegoIntegratedRegionalWaterManagementPlan2013).Section303(d)‐listedimpairedinlandsurfacewatersarefoundineachoftheregion’swatersheds.Additionally,eachoftheregion’swatershedscontainsatleastonecoastalwaterorbeachsegmentthatiscurrentlylistedasimpaired.Examplesofthetypesofpollutants/stressorsforwhichthesewaterbodiesareimpairedincludesedimentation,totaldissolvedsolids,bacteriaindicators,fecalcoliform,phosphorus,cadmium,copper,anddiazinon(CountyofSanDiego2007e).
Water Quality Contaminants
Commonwaterqualitycontaminantsintheregionaredescribedbelow(CountyofSanDiego2011a).
Metals
Metalscanaffectsurfacewaterqualitybyaccumulatinginsedimentsandfishtissues.Thisposesrisksoftoxicitysuchasloweringthereproductiveratesandlifespansofaquaticanimalsandanimalsupthefoodchain.Metalscanalsoalterphotosynthesisinaquaticplantsandformdepositsinpipes.Metalsinurbanrunoffcanresultfromautomobileuse,industrialactivities,watersupplyinfrastructurecorrosion,mining,orpesticideapplication.Atmosphericdepositioncanalsocontributemetalstowaterbodies.
Nutrients (Phosphorous and Nitrogen)
Highlevelsofnitrogenandphosphorusinsurfacewaterscanproduceharmfulalgalblooms.Inturn,thesebloomscanproducedeadzonesinwaterbodieswheredissolvedoxygenlevelsaresolowthatmostaquaticlifecannotsurvive.Typicalsourcesofnutrientsinsurfacewatersareimproper
Figure 2.5-1Watersheds
County of San Diego Agriculture Promotion Program
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Figure 2.5-2Reservoirs
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fertilizerusage(bothagriculturalandresidential),dischargesfromfailingorimproperlymaintainedsepticsystems,andaccidentalsanitaryseweroverflows.Nitrate,whichiscomposedofnitrogenandoxygen,occursnaturallyinsoilandwater.Nitrateisanimportantconstituentinfertilizersusedforagriculturalpurposesandispresentinhumanandanimalwastes.
Petroleum Products (Gasoline, Diesel, Oil, and Grease)
Gasoline,diesel,oil,andgreasearecharacterizedashighmolecularweightorganiccompounds.Primarysourcesofgasoline,diesel,oil,andgreasecontaminantsaremotorproductsfromleakingvehiclesandundergroundstoragefacilitiesandtanks.Petroleumhydrocarbonproductscommonlyfoundingasoline,includingbenzene,toluene,ethylbenzene,xylene,andmethyltert‐butylether(MTBE),areconsideredcommonpetroleumcontaminantstosurfacewaterandgroundwater.Benzeneisusedasagasolineadditiveandindustrialsolventandisusedintheproductionofdrugs,plastics,rubber,anddyes.Tolueneiswidelyusedasanindustrialfeedstockandasasolvent.Ethylbenzeneisusedintheproductionofplastic,whilexyleneisusedasasolventintheprinting,rubber,andleatherindustries.MTBEisagasolineadditivethathashistoricallycausedgroundwatercontaminationfromspillsorleaksatgasstations.Introductionofpetroleumpollutantstowaterbodiesistypicallyduetothewidespreaduseandapplicationoftheseproductsinmunicipal,residential,commercial,industrial,andconstructionareas.
Additionalsourcesofoilandgreaseincludeesters,oils,fats,waxes,andhighmolecular‐weightfattyacids.Introductionofthesepollutantstowaterbodiesistypicalduetothewidespreaduseandapplicationoftheseproductsinmunicipal,residential,commercial,industrial,andconstructionareas.Elevatedoilandgreasecontentcandecreasetheaestheticvalueofawaterbody,aswellasitswaterquality.
Pathogens (Bacteria and Viruses)
Watercontaminatedwithpathogenssuchasbacteriaandvirusescanintroducediseasestohumansandanimals.Thiscanhavesignificantpublichealthimplications,particularlyrelatedtowaterusedfordrinking,recreationsuchasswimmingandsurfing,andshellfishharvesting.Commonsourcesofpathogensinsurfacewaterincludewildanddomesticatedanimals,urbanandagriculturalactivities,andaccidentalsanitaryseweroverflows.
Pesticides and Herbicides
Pesticidesandherbicidescanentersurfacewaterandgroundwaterfrombothagriculturalandurbanareas.Typicalimpactsincludeaccumulationinsedimentsandbioaccumulationinthefoodchain.Pesticidesandherbicidescanbetoxictobothaquaticlifeandhumans.
Sediments
Increasedsedimentation,overandabovetheamountthatentersthewatersystembynaturalerosion,cancausemanyadverseimpactsonaquaticorganisms,watersupply,andwetlands.Sedimentationcandecreasetransmissionoflight,whichaffectsplantproductionandleadstolossoffoodandcoverforaquaticorganisms.Itcanchangebehavioralactivities(nesting,feeding,mating),andadverselyaffectrespiration,digestion,andreproduction.Contaminantsandtoxicsubstancescanalsobetransportedinsediments.Sedimentscandamagewatertreatmentequipment,increasingtreatmentcosts.Theycanreducereservoirvolumeandfloodstorageandincreasepeakdischarges.
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Total Dissolved Solids
Totaldissolvedsolids(TDS)refertothetotalconcentrationofallminerals,salts,metals,cations,oranionsthataredissolvedinwater.TDSiscomposedofinorganicsalts(principallycalcium,magnesium,potassium,sodium,bicarbonate,carbonate,chloride,andsulfate)andsomesmallamountsoforganicmatterthataredissolvedinwater.Increasedsaltsinregionalfreshwaterresourcesfrommining,urbanrunoff,andconstructioncancreatestressfulenvironmentsandevendestroyhabitatandfoodsourcesforwetlandanimalsinaquaticandwetlandhabitats,aswellasfavoringsalt‐tolerantspecies;reducethequalityofdrinkingwater;andmaycauseskinoreyeirritationsinpeople.AnelevatedTDSconcentrationisnotahealthhazard;however,itcancausethewatertohaveasaltyorbrackishtaste,andtobecorrosive,andresultsinscaleformationonpipes,pumps,waterheaters,etc.BecauseoftheseasonalnatureofprecipitationwithintheSanDiegoregion,surfacinggroundwaterandrunofffromappliedwater(agriculturalandurban)representtheprimarycontributorstodryseasonstreamflows.Theinterchangebetweensurfacewaterandgroundwater,andtheextremeseasonalvariabilityofflow,evaporation,andwaterqualityinSanDiegoCountyallcontributetoawiderangeofTDSintheregion’ssurfacewaters.ItisalsoofnotethatmuchofthewaterimportedtotheSanDiegoregionisrelativelyhighinTDScontent.
2.5.1.3 Groundwater Quality
GroundwaterobtainedfromSanDiegoCountyaquifershastraditionallybeenofhighquality.However,naturallyoccurringand,morerecently,man‐madesourcesofcontaminationhaveadverselyaffectedthegroundwaterqualityinlocalizedareas.Themostcommonman‐madesourcesofgroundwatercontaminationincludingleakingundergroundfueltanks,sewerandsepticsystems,agriculturalapplications,andfacilitiesproducinganimalwastes.ThemostcommoncontaminantsingroundwaterwithinSanDiegoCountyincludeelevatednitratelevels,naturallyoccurringradionuclides,TDS,andbacteria.Groundwatercontaminantsofconcernthatmayresultfromagriculturaloperationsmayinclude:herbicides,pesticidesandothercomplexorganics;petroleumproductsincludingMTBEandvolatileorganiccompounds;andmetals.
2.5.1.4 Soil Erosion
AsdiscussedaboveunderSediments,soilerosioncanleadtowaterqualityproblemsassociatedwithincreasedturbidityandsedimentation.Soilerosionisdependentonanumberoffactors,suchassoilproperty,levelofforce,andlandscapecharacteristics.Erosionisanaturalprocesscausedbywater,wind,mechanical,orchemicalforcesactingonexposednaturallandforms.Thissectiondescribeserosionbywater.
Soilsandsedimentarecomposedofsmallpiecesofdecomposedrockmaterialsuchassand,gravel,loam,clay,orsiltthatalsocontainvaryingamountsoforganicmaterials.Erosionremovessoil,sediment,androckfromexposedareasandtransportstheresultingtopsoilandsediment.Theresultsincludespreadingofcontaminantsandthereducedabilityofsoiltostorewaterandsupportplantgrowth,therebyreducingitsabilitytosupportbiodiversity.Erodedmaterialsfillreservoirs,ponds,anddrainageditchesandsiltupharbors,streams,andrivers.
Measuring Soil Erosion
Therateoferosionisdependentonthetypeofmaterialthatiseroded,thetypeandamountoferosiveforces,andtheshapeofthelandforminvolved.Soilshaveuniquepropertiesthatmakethemmoreorlesssusceptibletoerosion.Forexample,soilaggregatematerialsuchasveryfinesand,silt,
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clay,andorganicmattercanbeeasilyremovedbyraindropsplashandrunoffwater;greaterraindropenergyorrunoffamountsmightberequiredtomovethelargersandandgravelparticles.Thetypeandamountoferosionalforceaffectstheerosionalrateandisprimarilyaffectedbythedurationandintensityofaprecipitationeventandbytheslopeofthesite.
Runoffoccurswheneverexcesswateronaslopecannotbeabsorbedintothesoilortrappedonthesurface.Theamountofrunoffcanbeincreasedifinfiltrationisreducedduetosoilcompaction.Runofffromagriculturallandmaybegreatestduringspringmonthswhensoilsmaybesaturatedandvegetativecoverisminimal.
TheU.S.DepartmentofAgriculture’sSoilSurveyfortheSanDiegoAreaconductedin1973ratedandclassifiedeachsoil’sleveloferodibilitytypicalofthatclass.Aratingofslight,moderate,orseverewasappliedtoeachclassificationbasedonthecriteriashowninTable2.5‐1.Thetableidentifiesfourfactorsthataffecttheerodibilityofasoiltype.Notethatclimate,plantcover,andphysiographicfeaturesarenotapartoftheratingsystemforerodibilityasthesefactorsvaryindependentofthesoilclassificationtype(CountyofSanDiego2007e).MostoftheexistingagriculturaluseinSanDiegoCountyoccursinnon‐primesoils.SanDiegoCountyhasgenerallysteepterrainanderodiblesoils,andlowrankingsgenerallyresultfromtheimportanceofslopeanderodibilityintheformulasthatdeterminethesoilratings(CountyofSanDiego2002).
2.5.1.5 Stormwater Drainage Systems
Stormwaterdrainagesystemsconveyurbanrunoffandarerelatedtowaterqualityconditions.Thesesystemsaredesignedtopreventfloodingbytransportingwaterawayfromdevelopedareas.AvastamountoftheunincorporatedSanDiegoareaisrurallandthatdoesnotsupportorrequirestormwaterdrainagefacilities.Inmoreruralandremoteareasstormwaterdrainagefacilitiesaremainlylimitedtoroadsideditchesandculverts.Incontrast,moredevelopedareashavearangeofstormwaterdrainagefacilitiessuchasstormdrains,concretedrainagepipes,improvedchannels,culverts,guttersandditches,anddetentionbasins.
Changestostormwaterflows(suchasincreasedvolumeoralteredpaths)cancausesiltation,flooding,and/orerosion,whichinturncanleadtopropertylossandenvironmentaldamage.Unfilteredanduntreatedstormwatercancontainanumberofpollutantsthatmayeventuallyflowtosurfacewaters.Stormwaterdischargesthatenterthereceivingwaterscanbepollutedbyeitherpointsourcesornon‐pointsources.Pointsourcesaredefinedaswaterpollutioncomingfromasinglepoint,suchasasewage‐outflowpipe.Non‐pointsourcesaredefinedaspollutiondischargedoverawidelandare,notfromonespecificlocation(U.S.GeologicalSurvey2015a).
2.5.2 Regulatory Setting
Hydrologicalresourcesandwaterqualityconditionsaresubjecttoregulatoryoversightatthreelevels:federal,state,andregional/local.
2.5.2.1 Federal Regulations
Federal Water Pollution Control Act (Clean Water Act)
IncreasingpublicawarenessandconcernforcontrollingwaterpollutionledtoenactmentoftheFederalWaterPollutionControlActAmendmentsof1972.Asamendedin1977,thislawbecamecommonlyknownastheCWA.TheCWAestablishedbasicguidelinesforregulatingdischargesof
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pollutantsintothewatersoftheUnitedStates,andrequiresthatstatesadoptwaterqualitystandardstoprotectpublichealth,enhancethequalityofwaterresources,andensureimplementationoftheCWA(U.S.Code,Title33,Section1251etseq.)inthefollowingways.
Section401requiresanapplicationforafederalpermit,suchasfortheconstructionoroperationofafacilitythatmayresultinthedischargeofapollutant,toobtaincertificationofthoseactivitiesfromthestateinwhichthedischargeoriginates.Thisprocessisknownaswaterqualitycertification.ForprojectsintheCounty,theRWQCBissuesSection401permits.
Section402establishedtheNationalPollutantDischargeEliminationSystem(NPDES)tocontrolwaterpollutionbyregulatingpointsourcesthatdischargepollutantsintowatersoftheUnitedStates.IntheStateofCalifornia,theU.S.EnvironmentalProtectionAgency(EPA)hasauthorizedtheStateWaterResourcesControlBoard(SWRCB)permittingauthoritytoimplementtheNPDESprogram.Ingeneral,theSWRCBissuestwobaselinegeneralpermits:oneforindustrialdischargesandoneforconstructionactivities.ThePhaseIIRulethatbecamefinalonDecember8,1999,expandedtheexistingNPDESprogramtoaddressstormwaterdischargesfromconstructionsitesthatdisturblandequaltoorgreaterthan1acre.
Section404establishedapermittingprogramtoregulatethedischargeofdredgedorfillmaterialintowatersoftheUnitedStates.ThedefinitionofwatersoftheUnitedStatesincludeswetlandsadjacenttonationalwaters.ThispermittingprogramisadministeredbytheU.S.ArmyCorpsofEngineersandisenforcedbyEPA.
Section303(d)requiresSWRCBtodevelopalistofwaterqualitylimitedsegmentsforjurisdictionalwatersoftheUnitedStates.TheRWQCBsareresponsibleforestablishingpriorityrankingsanddevelopingactionplans,referredtoastotalmaximumdailyloads(TMDLs),toimprovethewaterqualityofwaterbodiesincludedinthe303(d)list.Themostrecent303(d)listapprovedbyEPAisfrom2010.Thelistincludespollutantscausingimpairmenttoreceivingwatersor,insomecases,theconditionleadingtoimpairment.
Federal Maximum Contaminant Levels
Toprotectpublichealthrelatedtoknowncontaminantsindrinkingwatersupplies,EPAsetsthehighestlevelofacontaminantforarangeofcontaminants,includingmicroorganisms,disinfectantsanddisinfectionbyproducts,andchemicals,amongothers.Therearetwotiers:primaryandsecondarystandards.NationalPrimaryDrinkingWaterRegulations(primarystandards)areenforceablestandards.NationalSecondaryDrinkingWaterRegulations(secondarystandards)areguidelinesrelatedtocontaminantsthatcouldcauseaestheticeffects(suchastaste,odor,orcolor)orcosmeticeffects(suchasskinortoothdiscoloration).
National Pollutant Discharge Elimination System
EPAhasdelegatedresponsibilityforimplementingportionsoftheCWAtoSWRCBandtheRWQCBs,includingwaterqualityplanningandcontrolprograms,suchastheNPDESprogram.TheNPDESprogramisbasedonpermitsdesignedtoimplementtheCWA;thesepermitsapplytovariousactivitiesthatgeneratepollutantswiththepotentialtoimpactwaterquality,aswellasstormwaterdischargesassociatedwithurbanareasandcertainindustrialactivities.EPAhasdevelopedatwo‐phasedNPDESpermittingprogram(PhaseIandPhaseII)thatrequirescitiesandotherlocalentitiestoobtainmunicipalstormwaterNPDESpermitsthatmandatetheimplementationofstormwatermanagementprograms,includingmethodstoreducepollutantsinstormwaterrunoff.
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PhaseIregulatesstormwaterdischargesfrommediumandlargemunicipalseparatestormsewersystems(MS4s),constructionactivitiesinvolvingareas5acresorlarger(orlessthan5acresifpartofacommonplanofdevelopmentorsale),andindustrialactivities.PhaseIIextendstheregulationstostormwaterdischargesfromsmallMS4sandconstructionactivitiesthatdisturbareasequaltoorgreaterthan1acreofland(orlessthan1acreifpartofacommonplanofdevelopmentorsale).ThroughtheuseofNPDESpermits,PhaseIIalsoexpandsthePhaseIprogrambyrequiringoperatorsofMS4sinurbanizedareasandoperatorsofsmallconstructionsitestoimplementprogramsandpracticestocontrolpollutedstormwaterrunoff.
2.5.2.2 State Regulations
Section 303(d) List of Water Quality Limited Segments
Section303(d)oftheCWArequiresstatestoidentifywatersthatdonotmeetwaterqualitystandardsafterapplyingcertainrequiredtechnology‐basedeffluentlimits.Thesearereferredtoasimpairedwaterbodies.The2010CWA303(d)ListofWaterQualityLimitedSegments(CaliforniaEnvironmentalProtectionAgency2015)classifiestheimpairedwaterbodieslocatedintheCounty.Thecomplete2010EPA‐approvedlistfortheSanDiegoRegionisavailablefromtheSanDiegoRWQCBatthefollowingwebaddress:http://www.swrcb.ca.gov/sandiego/water_issues/programs/303d_list/index.shtml.
Oncelistedasimpaired,waterbodysegmentsaretargetedforaTMDLrestorationplantoimprovewaterquality.ATMDLisaquantitativeassessmentofwaterqualityproblems,contributingsources,andloadreductionsorcontrolactionsneededtorestoreandprotectbodiesofwater.TMDLsareadoptedasamendmentstotheBasinPlan(SanDiegoRWQCB2011).
Waste Discharge Requirements
Ingeneral,theState’sWasteDischargeRequirements(WDRs)Program(sometimesalsoreferredtoasthe“NonChapter15[Non15]Program”)regulatespointdischargesthatareexemptpursuanttoSubsection20090ofTitle27andnotsubjecttotheCWA.ExemptionsfromTitle27maybegrantedforninecategoriesofdischarges(e.g.,sewage,wastewater)thatmeet,andcontinuetomeet,thepreconditionslistedforeachspecificexemption.ThescopeoftheWDRsProgramalsoincludesthedischargeofwastesclassifiedasinert,pursuanttoSection20230ofTitle27.
OneofthecoreregulatoryelementsistheIrrigatedLandsRegulatoryProgram,whichregulatesdischargesfromirrigatedagriculturallandstopreventagriculturaldischargesfromimpairingthewatersthatreceivethesedischarges.ThisisdonebyissuingWDRsorconditionalwaiversofWDRs(Orders)togrowers.TheseOrderscontainconditionsrequiringwaterqualitymonitoringofreceivingwatersandcorrectiveactionswhenimpairmentsarefound.ThereareaboutsixmillionagriculturalacresenrolledintheIrrigatedLandsRegulatoryProgramandapproximately40,000growers(SWRCB2015b).
Porter‐Cologne Water Quality Control Act
ThePorter‐CologneWaterQualityControlAct(CaliforniaWaterCode,Division7)providesultimateauthoritytotheSWRCBtoadopt,review,andrevisepoliciesforallwatersoftheState(includingbothsurfacewatersandgroundwaters).NineRWQCBswereestablishedtoprovideoversightonwaterqualityissuesataregionalandlocallevel.Section13170oftheCaliforniaWaterCodealsoauthorizesSWRCBtoadoptwaterqualitycontrolplansonitsowninitiative.TheWaterQuality
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ControlPlanfortheSanDiegoBasin(Region9)isdesignedtopreserveandenhancethequalityofwaterresourcesintheSanDiegoRegionforthebenefitofpresentandfuturegenerations.ThepurposeoftheplanistodesignatebeneficialusesoftheRegion’ssurfacewatersandgroundwaters,designatewaterqualityobjectivesforthereasonableprotectionofthoseuses,andestablishanimplementationplantoachievetheobjectives.
Streambed Alteration Agreement
Sections1601–1603oftheCaliforniaFishandGameCoderequireanagreementbetweentheCaliforniaDepartmentofFishandWildlifeandapublicagencyproposingtosubstantiallydivertorobstructthenaturalfloworaffectchangestothebed,channel,orbankofanyriver,stream,orlake.Theagreementisdesignedtoprotectthefishandwildlifevaluesofariver,lake,orstream.
2.5.2.3 Regional/Local Regulations
San Diego Regional Water Quality Control Board Basin Plan
TheSanDiegoRWQCBBasinPlanwasapprovedbySWRCBin1994andwasmostrecentlyrevisedin2011.TheRWQCBdesignatesbeneficialusesintheBasinPlanunderCaliforniaWaterCodeSection13240.Beneficialusesaredefinedaswaterusesnecessaryforthesurvivalorwell‐beingofhumans,plants,andwildlife.Designatedbeneficialusesininlandsurfacewaters,coastalwaters,reservoirsandlakes,andgroundwaterintheCountyareidentifiedinTables2‐2through2‐5oftheBasinPlan.
San Diego Regional Water Quality Control Board Order No. R9‐2007‐0104, Conditional Waiver No. 4
ConditionalWaiverNo.4isfordischargesfromagriculturalandnurseryoperations,whichcontainpollutantsthatcanpercolatetogroundwaterorrunofftosurfacewaters.Dischargesfromagriculturalandnurseryoperationsincludedischargesresultingfromgrowingoperations,irrigationreturnflows,andstormwaterrunoffthatcantransportpollutantsfromagriculturalandnurseryoperationstosurfacewatersandgroundwater.AgriculturalandnurseryoperationsthatcomplywiththewaiverconditionsarenotexpectedtoposeathreattothequalityofwatersoftheState.
ThefollowingtypesofdischargearenotregulatedorauthorizedunderWDRsandmaybeeligibleforaConditionalWaiverNo.4.
Dischargesofplantcropresiduestoland
Dischargesofstormwaterrunoff
Discharge/applicationofamendmentsormulchestosoil
Dischargesofagriculturalirrigationreturnwater
Dischargesofnurseryirrigationreturnwater
ConditionalWaiverNo.4wasadoptedinOctober2007andexpiredinFebruary2014.TheSanDiegoRWQCBisdevelopingTentativeGeneralWasteDischargeRequirementsforDischargesofWastesfromCommercialAgriculturalandNurseryOperationswithintheSanDiegoRegion(GeneralAgriculturalOrder)toreplacetheexpiredAgriculturalWaiver.TheSanDiegoRWQCBistentativelyscheduledtoconsideradoptionoftheTentativeGeneralOrderin2016.Therewere50,000
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agriculturalacresandbetween2,200and2,500agriculturaloperationsenrolled(SWRCB2015c;Pulverpers.comm.).
San Diego Regional Water Quality Control Board Regional MS4 Permit
TheRegionalMS4PermitisusedtoregulatedischargesfromPhaseIMS4sintheSanDiegoRegion.TheRegionalMS4Permitcovers39municipal,countygovernment,andspecialdistrictentities(referredtojointlyasCopermittees)locatedinSanDiegoCounty,southernOrangeCounty,andsouthwesternRiversideCountywhoownandoperatelargeMS4swhichdischargestormwater(wetweather)runoffandnon‐stormwater(dryweather)runofftosurfacewatersthroughouttheSanDiegoRegion(SanDiegoRWQCB2015).Underthispermit,eachmunicipalitymustdevelopastormwatermanagementprogramdesignedtocontrolthedischargeofpollutantsintoandfromtheMS4(orfrombeingdischargeddirectlyintotheMS4).Thepurposeistoprotectlocalwaterbodiessincestormdrainstypicallydischargetheirwaterintostreams,bays,and/ortheoceanwithouttreatment.OrderNo.R9‐2013‐0001,asamendedbyOrderNos.R9‐2015‐0001andR9‐2015‐0100,presentsguidelinerequirementsforthecontrolofpollutantsresultingfromstormwaterandurbanrunoff.
County of San Diego Code of Regulatory Ordinances, Sections 67.801–67.814, Watershed Protection, Stormwater Management, and Discharge Control Ordinance
TheCountyWatershedProtection,StormwaterManagement,andDischargeControlOrdinance(WPO)wasadoptedinMarch2008andrevisedinJune2015.ThepurposeoftheWPOistoprotectwaterresourcesandimprovewaterqualitybycontrollingthenon‐stormwaterconveyancesystemandreceivingwaters,torequiretheuseofmanagementpracticesbytheCountyanditscitizensthatwillreducetheadverseeffectsofpollutedrunoffdischargesonwatersoftheState,tosecurebenefitsfromtheuseofstormwaterasaresource,andtoensuretheCountyiscompliantwithstateandfederallaw.TheWPOestablishesstandardsandrequirementsthatarelegallyenforceablebytheCountywithintheCounty’sjurisdiction.Projectsthatrequireapermit(e.g.,AdministrativePermit,MajorUsePermit,GradingPermit)arerequiredtodemonstratecompliancewiththeWPO.Section67.804,forexample,specificallyaddresseswastedischargeandprohibitsthedischargeofpollutantstothestormwatersystemunlesspermittedthroughtheNPDESProgram.
Aspartoftherevisedordinance,prioritydevelopmentprojectsarerequiredtoincorporateLowImpactDevelopment(LID)techniques.Adoptedin2008,theLIDHandbookwasprovidedtocomplementtheWPObyprovidingguidanceregardingLIDtechniquesandpractices.LIDdesignconsiderationsforproposedprivateprojectsmayincludethefollowing:(1)drainingrunofffromimperviousareasintoperviousareasbasedonthecapacitytotreat/holdrunoff;(2)designingperviousareastoreceiveandtreatrunoffbyusingswales,detention,and/orbioretention,andusingamendedsoilstoincreaseinfiltration;(3)usingporouspavementswhereappropriate;(4)conservingnaturalareas,trees,vegetation,andsoils;(5)constructingstreets,sidewalks,andparkingareastotheminimumwidthsnecessaryforpublicsafety,therebyretainingperviousareas;(6)minimizingtheimperviousfootprintoftheprojectanddisconnectingimpervioussurfaces;(7)minimizingsoilcompaction(underplannedgreen/openareas);and(8)minimizingdisturbancetonaturaldrainages.
County of San Diego Section 2.5. Hydrology and Water Quality
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County Code of Regulations Related to Groundwater Well Water Quality
Section67.401oftheCountyCodeofRegulationsprovidesrestrictionsandregulationsforwells.Thestandardsinthecodeapplytotheconstructionandmaintenanceofwellstoensurethatgroundwaterwillnotbepollutedorcontaminated.PrivatedrinkingwaterwellsrequireapermitfromtheCountyDepartmentofEnvironmentalHealth.Aspartofthisprocess,newwellsaresampledforbacteriologicalconstituentsandnitrate.
Forprojectswithpoorgroundwaterquality,twomitigationmeasureshavebeenidentifiedbytheCountyinadditiontoimportingwatertotheprojectsite.Thefirststatesthatforprojectswhereanyconstituentexceedsitsprimarymaximumcontaminantlevelandadiscretionarypermitrequiresapotablegroundwatersupply,mitigationcouldbeimplementedbyprovidingawatertreatmentsystemthatreducesimpactstobelowthemaximumcontaminantlevel.ToensureproperwatertreatmentinaccordancewiththeCaliforniaSafeDrinkingWaterAct,theCountyrequiresdiscretionarypermitsthatrequiretreatmenttoformormergewithawatersystemregulatedbytheCountyDepartmentofEnvironmentalHealth(upto200serviceconnections)orthestate(greaterthan200serviceconnections).Thisensurespropertreatmentofconstituentsanddoesnotplacetheresponsibilityoftreatmentonprivateindividuals.AlthoughtheCountywillallowpoint‐of‐useorpoint‐of‐entrytreatmentforcontaminantsinwellsonexistinglegallots,itwillnotapprovediscretionarypermitsforprivatewellsdependentonwatertreatment.Thesecondmitigationmeasurestatesthatadditionalwellsandtestingcanbeconductedinanattempttofindonsitepotablewater.Drillingandtestingadditionalwellsisexpensiveandtime‐consuming,andtherearenoguaranteesthatthenewwell(s)willhaveapotablewatersupply(CountyofSanDiego2011a).
County of San Diego Grading Ordinance
ThepurposeoftheGradingOrdinanceistocombineregulationsaffectingthegradingandclearingoflandandactivitiesaffectingwatercourseswithintheunincorporatedpartsoftheCounty.Chapter6(Sections87.601–87.608)oftheordinancecoverswatercoursesandisintendedtoprotectpersonsandpropertyagainstfloodhazardsbyidentifyingprohibitedactsinwatercoursesandactsthatareprohibitedunlessapermitisobtained.Theordinancerequiresthatprojectsinvolvingmorethan200cubicyardsofgrading,clearing,and/orremovalofnaturalvegetationobtainaGradingPermit(seeSection1.5.1,MatrixofProjectApprovals/Permits).GradingPermitsarediscretionaryandrequirecompliancewithCEQA.
Pesticide Regulation Program
TheCounty’sPesticideRegulationProgramisthelocalprogramoverseenbytheCountyAgriculturalCommissionerandDepartmentofAgriculture,Weights,andMeasures.Permitsarerequiredanytimepesticidesareappliedtoagriculturallands,whetherbyanowner/operatororacontractedentity.Whenapplyingforapermit,theapplicantmustprovideinformationincludingthelocationandacreageofthepropertytobetreated,andknownlocationsnearbythatcouldbeadverselyaffectedbythepesticideusesuchaslakes,waterways,andreservoirs.IftheAgriculturalCommissionerdeterminesthatthepermitwouldlikelycauseasubstantialadverseimpact,thecommissionermustdetermineifthereisafeasiblealternative(includingnopesticideapplication)orafeasiblemitigationmeasurethatwouldsubstantiallyreducetheadverseimpact.Ifthereisnofeasiblealternativeormitigationmeasure,thecommissionermustdenythepermit.TheDepartmentofAgriculture,Weights,andMeasuresmaintainsadatabaseofpesticideapplicationsintheCounty
County of San Diego Section 2.5. Hydrology and Water Quality
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thatincludesthenameandaddressoftheapplicant,dateofapplication,croptype,andtypeofpesticideused.
San Diego County Hydrology Manual
ThepurposeofthismanualistoprovideauniformprocedureforfloodandstormwateranalysiswithinSanDiegoCounty.ItprovidesaguideforpoliciesandproceduresbaseduponthescienceanddataavailabletoattainreasonablestandardizationofhydrologystudiesthroughouttheCounty.
San Diego County Drainage Design Manual
ThismanualestablishesdesignstandardsandproceduresforstormwaterdrainageandfloodmanagementfacilitiesinSanDiegoCounty.Thesedesignstandardsandproceduresprovideguidanceforjurisdictionsintheselection,design,construction,andmaintenanceofstormwaterdrainageandfloodmanagementfacilities.
2.5.3 Analysis of Project Effects and Determination of Significance
TheproposedprojectconsistsofanamendmenttotheZoningOrdinancerelatedtoaccessoryagriculturalusesinunincorporatedportionsoftheCountyoverwhichtheCountyhaslandusejurisdictions(seeSection1.4,ProjectDescription,forfurtherdetails).Specifically,theproposedprojectappliestopropertieswhereactiveagricultureexistswithintheCountyorpropertieswhereagriculturalusesareallowed.DuringtheInitialStudypreparationandscopingprocessforthisproject,whichconsideredpotentiallysignificantenvironmentalimpactsandinvolveda30‐daypubliccommentperiod,itwasdeterminedthattheproposedprojectwouldnotresultinasignificantimpactrelatedtoplacinghousingwithina100‐yearfloodhazardarea,asmappedonafederalFloodHazardBoundaryorFloodInsuranceRateMaporotherfloodhazarddelineationmap,orplacewithina100‐yearfloodhazardareastructuresthatwouldimpedeorredirectfloodflows.Therewouldalsobenopotentialfortheproposedprojecttoresultinasignificantimpactrelatedtoexposingpeopleorstructurestoasignificantriskofloss,injury,ordeathinvolvingflooding,includingfloodingasaresultofthefailureofaleveeordam,orcontributionstoinundationbyseiche,tsunami,ormudflow.Assuch,potentialimpactsrelatedtofloodhazardsandinundationarenotevaluatedbelow.FurtherdiscussionisavailableintheInitialStudypreparedfortheproposedproject,whichisprovidedasAppendixB.
Threecommentlettersthatarerelevanttohydrologyandwaterqualitywerereceivedduringthe30‐daycommentperiod.EricMarchofStarBBuffaloRanch&HopFarmrequestedinformationonhydrologytestingrequirements.TheCityofSanDiegoindicatedthatwaterqualityisofconcernparticularlybecauseofthedrinkingwaterreservoirsthatitownsintheCounty.TheClevelandNationalForestindicatedthatwaterqualityisofparticularconcernfortheagencyandrequestedthattheEIRconsidereffectsofintensifiedlandusesontheforest.
County of San Diego Section 2.5. Hydrology and Water Quality
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2.5.3.1 Water Quality
Guidelines for the Determination of Significance
ThefollowingsignificanceguidelinesfromAppendixGoftheStateCEQAGuidelinesapplytoboththedirectandcumulativeimpactanalyses.Asignificantimpactwouldoccuriftheproposedprojectwould:
Violateanywaterqualitystandardsorwastedischargerequirements.
Otherwisesubstantiallydegradewaterquality.
Analysis
Oneoftheprimaryobjectivesoftheproposedprojectistostreamlineandclarifytheapproval/permittingforaccessoryagriculturaloperationswithintheCounty,whileensuringcompliancewithlocal,state,andfederalregulationswhereappropriateandutilizingsoundmanagementpractices.Thisobjectivewouldprovideincreasedopportunitiesforagriculturalventuresandtourismthatareaccessorytoexistingagriculturaloperations.Thus,theproposedprojectwouldpromoteandencourageadditionallanduseactivitiesonactiveagriculturallandthroughoutunincorporatedSanDiegoCountyforsuchoperationsasmicrobreweries,cheese‐makinganddairyoperations,onsitefoodproduction,mobilebutchering,packingandprocessing,onsiteretailhorticulturesales,animalraising,roadsidesalesofagriculturalproducts,agriculturaltourism,andagriculturalhomestays.AlthoughtheactionofamendingtheZoningOrdinancewouldnotdirectlyresultinhydrologyandwaterqualityimpacts,theusesthatitencouragesmay.Thesepotentialimpactscangenerallybegroupedintotwomajorcategories—construction‐relatedandoperationalimpacts—whicharediscussedfurtherinthefollowingsections.Followingthisdiscussion,theanticipatedimpactsspecifictotheaccessoryagriculturaloperationspromotedbytheproposedprojectareaddressed.
General Construction Related Impacts
Theproposedprojectwouldpromoteandencourageadditionallanduseactivitiesonactiveagriculturalland.Anindirectresultofthiscouldbeincreasedconstructionanddevelopmentonsomeagriculturalproperties.Constructionanddevelopmentactivitiessuchasdemolition,clearingandgrading,excavationofundocumentedfillmaterials,stockpilingofsoilsandmaterials,concretepouring,painting,andasphaltsurfacing,havethepotentialtoresultinadditionalsourcesofpollutedrunoffwhichcouldhaveshort‐termimpactsonsurfacewaterquality.Typically,constructionactivitiesinvolvevarioustypesofequipmentsuchasdozers,scrapers,graders,loaders,compactors,dumptrucks,cranes,watertrucks,andconcretemixers.Duringconstruction,soilsaretypicallystockpiledoutdoors,asareotherconstructionmaterialsforlateruse.Pollutantsassociatedwithsuchactivitiesthatmaydegradewaterqualityincludesoils,debris,othermaterialsgeneratedduringdemolitionandclearing;fuelsandotherfluidsassociatedwiththeequipmentusedforconstruction;paints;otherhazardousmaterials;concreteslurries;andasphaltmaterials.Pollutantsassociatedwithconstructionwoulddegradewaterqualityiftheyarewashedbystormwaterornon‐stormwaterintosurfacewaters.
Sedimentisoftenthemostcommonpollutantassociatedwithconstructionsitesbecauseoftheassociatedearth‐movingactivitiesandareasofexposedsoil.Sedimentthatiswashedoffsitecanresultinturbidityinsurfacewaters,whichcanaffectaquaticspecies.Inaddition,whensedimentisdepositedintoreceivingwateritcansmotherspecies,alterthesubstrateandhabitat,andalterthe
County of San Diego Section 2.5. Hydrology and Water Quality
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drainagecourse.Hydrocarbonssuchasfuels,asphaltmaterials,oils,andhazardousmaterialssuchaspaintsandconcreteslurriesdischargedfromconstructionsitescouldalsoaffectaquaticplantsandanimalsdownstream.Debrisandtrashcouldbewashedintoexistingstormdrainagechannelstodownstreamsurfacewatersandcouldaffectwildlifeaswellasaestheticvalue.Contaminantscouldalsoenterthesoilandcontaminategroundwaterthroughsedimentsthataretransportedbyautomobilesonroadways.
UndertheNPDESProgram,StormwaterPollutionPreventionPlans(SWPPPs)areprepared,andbestmanagementpractices(BMPs)identifiedintheSWPPPsareimplementedforconstructionsitesgreaterthan1acre,inordertoreducetheoccurrenceofpollutantsinsurfacewater.Additionally,anyconstructionrequiringaGradingPermitfromtheCountymust,ataminimum,identifystandardBMPsthatwouldbeimplementedthroughaStormWaterManagementPlan.TheseregulatoryprogramswouldensurethatmostconstructionactivitiescontinuetoimplementBMPsthatminimizedisturbance,protectslopes,reduceerosion,andlimitorpreventvariouspollutantsfromenteringsurfacewaterrunoff.Whilethesemeasureshelppreventdegradationofwaterqualityassociatedwithmostconstructionprojects,smallerconstructionactivities(orthoseconductedillegallywithoutpermits)wouldstillhavethepotentialtocontributepollutantssuchassoils,debris,andothermaterialsinquantitiesthatwouldexceedwaterqualitystandardsandotherwisesignificantlydegradewaterquality.
TillingofnativeorfallowlandforagriculturalproductionwouldbesubjecttotheGradingOrdinanceandwouldrequireanAdministrativePermitforclearingiftheareawasnotinagriculturalproductionatleast1oftheprevious5years.ThispermitisdiscretionaryandissubjecttoreviewunderbothCEQAandtheWPO.AmongthemanyrequirementsthatmustbecompletedbeforeanAdministrativePermitcanbeissuediscompliancewithPartF.3,StandardsApplicabletoDiscretionaryPermitActivitiesoftheCountyStormwaterStandardsManual.PartF.3providesperformancestandards,includingalistofBMPoptions,anumberofwhichmustbeincorporatedfromthefollowingcategories:(1)erosioncontrol,(2)sedimentcontrol,(3)offsitesedimentcontrol,(4)velocityreduction,(5)materialsmanagement,and(6)structuralBMPs.However,landthatwasinagriculturalproductionforatleast1ofthepreceding5yearsisconsideredactiveagricultureandwouldnotrequireaclearingpermit.
General Operational Impacts
Therearemanypotentialsourcesofpollutantsfromnormalusesofland,and,astheproposedprojectsupportstheexpandeduseofagriculturalproperties,ithasthepotentialtoincreasepollutant‐generatingactivities.Someofthestandardpollutantsourcesaresedimentdischargeduetoareasoflandleftbare;nutrientsfromfertilizers;householdhazardouswastethatisimproperlydisposedof,includingheavymetalsandorganiccompounds;trashanddebrisimproperlydisposedof;oilandgrease;byproductsresultingfromvehicleuse,includingheavymetals;bacteriaandviruses;andpesticidesfromlandscapingandagriculture.Generally,theseconstituentscanbereferredtoasnon‐pointsourcepollutants.
Increaseduseofagriculturalpropertiesasaresultoftheprojectwouldresultinthecontributionofnon‐pointsourcepollutionintosurfaceandgroundwaterbodies.Althoughitisnotexpectedthatnon‐pointsourcepollutantscausedfromthedevelopmentassociatedwiththeproposedprojectwouldviolatewaterqualitystandards,theseconstituentswouldbeexpectedtootherwisedegradewaterquality.
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Regulatoryprogramsareinplacetocontrolnon‐pointsourcepollutants.Projectsthatrequirediscretionaryreviewwouldbeassessedforpotentialimpacts,andthosethathaveagreaterpotentialtoresultinpollutantsmayberequiredtopreparepost‐constructionstormwatermanagementplans.LargerconstructionprojectsarealsorequiredtoimplementtreatmentBMPsthatremovepollutantsfromstormwaterdischarges.
TheCountyofSanDiegoWPOprohibitsnon‐stormwaterdischargesandthedischargeofpollutantsfrompropertiesintheunincorporatedareasoftheCounty.Theuseofpesticides(whichincludeherbicides,insecticides,fungicides,androdenticides)inagriculturaloperationsisregulatedbytheCaliforniaDepartmentofPesticideRegulation.Intheprocessofreviewingapplicationsforpesticideuse,theDepartmentofPesticideRegulationmustdetermineeitherthatnoadverseimpactswouldresultorthatfeasiblemitigationwouldsubstantiallyreducetheadverseimpacts.Ifthereisnofeasiblealternativeormitigationmeasure,thepesticideapplicationpermitwouldbedenied.
Inaddition,pursuanttotheSanDiegoRWQCBResolutionNo.R9‐2007‐0104(ConditionalWaivers),allagriculturaloperationsintheCountyarerequiredtoimplementBMPstoensurethatnopollutantsleavethefarminirrigationorstormwaterdischarges,andaresubjecttoenrollment,monitoring,andreportingrequirementsintheRWQCBsConditionalWaiverNo.4(Resolution).TheResolutionallowsfortwooptionsforagriculturalandnurseryoperations:(1)operationsmayconducttestingandreportingasagroup,and(2)operationsmayactindividuallytosubmitplansandtestingresultsdirectlytotheRWQCB.Theresolutionappliestoallfutureagriculturaloperationsrelatedtotheproposedprojectbecausetheseusesarerequiredtogrowatleastaportionoftheirproductsonthepremisesoftheoperation.
Despitealltheseprograms,containmentofpollutantstoapropertyisnotguaranteed,andtheincreasedactivitiesthatwilllikelyresultfromtheproposedprojectwouldhavepotentialtoresultinpollutantdischarges.
Groundwater Quality Impacts
Groundwatercontaminationcanresultwhenman‐madeproductssuchasgasoline,oil,andchemicalsreachundergroundreservoirs,knownasaquifers.Whenthisoccurs,groundwatermayberenderedunsafeandunfitforhumanuse,andthelevelofgroundwateravailableforpotableusewouldlower.Theprimarycontaminantsofconcernthatcouldleachintogroundwatersuppliesasaresultofagriculturaloperationswouldbefromuseoffertilizers,herbicides,pesticides,petroleumproducts,volatileorganiccompounds,andorganicwastes.
Similartosurfacewaterquality,potentialcontaminantsfromfutureaccessoryagriculturaloperationswouldberequiredtocomplywithregulatoryprogramsinplacethatcontrolnon‐pointsourcepollutants.Projectsthatrequirediscretionaryreviewwouldbeassessedforpotentialimpacts,andthosethathaveagreaterpotentialtoresultinpollutantsmayberequiredtopreparepost‐constructionstormwatermanagementplans.LargerconstructionprojectsarealsorequiredtoimplementtreatmentBMPsthatremovepollutantsfromstormwaterdischarges.Furthermore,futureprojectswouldberequiredtocomplywiththeCountyofSanDiegoWPOandimplementBMPsinaccordancewiththeRWQCB’sConditionalWaivers.TheseregulationsrestrictthepollutantsandwaterthataredischargedfromanysiteandallowtheRWQCBtoenforcerestrictionsifnecessary.Therefore,potentialcontaminantsrelatedtotheproposedprojectarenotanticipatedtoreachgroundwatersuppliesandwouldnotsignificantlycontributetogroundwaterqualityissues.Impactsongroundwaterqualitywouldbelessthansignificant.
County of San Diego Section 2.5. Hydrology and Water Quality
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Accessory Agricultural Use Impacts
Thissectionisintendedtoprovideaconnectionfurtherdetailsbetweenthegeneralhydrologyandwaterqualityimpactsthataredescribedaboveandthespecificactivitiesthatmightbeanticipatedtooccurwiththeaccessoryagriculturalusescoveredbytheproposedproject.
Agricultural Homestay
Preparationforanagriculturalhomestayoperationcouldinvolveanexistinghomewithextraroomsandnogrounddisturbance,oritcouldincludeground‐disturbingactivitiessuchasgradingandtillinglandtoincreaseusableareaonaproperty,addingsignage,andexpandingbuildingstoaccommodateadditionalpeople.MostoftheseconstructionactivitieswouldtriggerbuildingorgradingpermitsandwouldrequireBMPstoaddressconstructionwaterqualityimpacts.However,somesmallerimprovementprojectswouldbeallowedwithoutpermitsandwouldnothavereviewforwaterqualityprotectionmeasures.Potentialpollutantsassociatedwithoperationofahomestaywouldbethosetypicalofresidentialandagriculturalpropertiessuchastrashanddebris,householdchemicals,andoilsandgreasefromvisitingvehiclesandotherequipment.AsdiscussedunderGeneralOperationalImpactsabove,thesesourcesofpollutantsaregenerallyunregulated,withtheexceptionoftheWPO,whichprohibitsthedischargeofanypollutants.
Agricultural Stores
Theproposedprojectwouldmaketheprocessforhavinganagriculturestorelessrestrictive.Ordinancesetbacks(Section4810),commercialbuildingcodes,andDepartmentofEnvironmentalHealthcompliancewouldstillberequired,whichwouldhelpguaranteesuchstoresarestillincompliancewithbuildingandhealthcoderequirements.TheimplementationoflargeandsmallagriculturalstorescouldincreasetheamountofimperviousbuildingcoverageintheunincorporatedCountybutwouldtypicallyrequirebuildingpermitsandaMinorStormWaterManagementPlan(SWMP).Aswithagriculturaltourismactivities,increasedvisitorsandassociatedpollutantswouldbeexpected.
Agricultural Tourism
Agriculturaltourismactivitiesaresimilartoagriculturalhomestaysinthattheycanoccurwithinthefootprintofexistingbuildingsoroutsideonopenfarmland,andoperationcouldincludeaddingsignage,expandingoralteringbuildings,anddemolitiontoaccommodateadditionalpeople.However,inthecaseofagriculturaltourism,theexpectationisthattheoperationwouldbeattractingagreaternumberofvisitors.Therefore,fromaconstructionperspectivetheremaybehigherdemandformoreusableareathusnecessitatinglargerconstructionprojects.Ontheoperationalperspective,morevisitorsgenerallymeansmorevehiclesandpeople,whichcanincreasethepotentialfortheirassociatedpollutantssuchastrash,debris,oils,andgrease.
Animal Raising
Theproposedprojectwouldamendthecurrentanimalscheduletoallowcertainanimalraisingprojectsunderalessrestrictiveadministrativepermit.Assuch,itislikelytheproposedprojectwouldcauseanincreaseofanimalsonagriculturallands,whichwouldsubsequentlyincreaseanimalwaste,whichcouldintroducesourcesofbacteriologicalcontaminationandelevatednitrates.
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Aquaponics
AquaponicswouldbeallowedunderSection6913oftheZoningOrdinanceunderaSpecialtyAnimalRaisingproject.Aquaponicswouldallowforfishfarminginasymbioticfishtank‐likeenvironmentandcouldinvolvegrounddisturbanceduringconstructionofabuildingtohousetheaquaponicscomponents.SuchabuildingwouldrequireabuildingpermitfromtheCountyandataminimumwouldtriggertherequirementsforaMinorSWMP.Aquaponicsoperateinaclosedloopsystem;therefore,thepotentialfornon‐stormwaterdischargesislow.Additionally,astheoperationwouldprimarilyconsistofacombinationofgrowingplantsandraisingfish,itwouldnotinvolvepollutantsintypesorquantitiesthatwouldbeofconcernwhencomparedtootheragriculturaloperations.
Creameries/Dairies
Implementationoftheproposedcreamery/dairyusescouldresultinindividualdevelopmentprojectsinvolvinglandclearingtosupportuptoa4,000‐square‐footbuilding;constructionofancillaryparkingareas,driveways,fences,andoutdoorseating;andanincreaseinsiteactivityrelatedtoadditionalvisitorsandnewemployees.Dependingonthesizeofthesubjectlotandthedesiredfacilitysize,acreamery/dairycouldproposeeithertheconstructionofanewbuildingoralterationofanexistingbuildingtohousetheequipmentforacreamery.Soildisturbanceresultingfromsoilclearing,grading,cutandfilloperations,andgeneralgrounddisturbancecouldincreasethepotentialforerosion,sedimentation,andnon‐permitteddischargesofmaterialsduringconstruction.However,mostconstructionactivitieswouldrequireabuildingorgradingpermitandataminimumwouldtriggertheneedforaMinorSWMP.Increasedvisitationtosuchafacilitywouldbesimilartoagriculturaltourism.
Fishermen’s Markets
Fishermen’smarketswouldallowthesaleoftheaquaponicallyraisedfishbyrightonpublicproperty,schoolpropertywithaschooluseorwithinC31,C32,C34,C35,C36,C37,C40,C42,orS88zones.Noconstructionwouldbeinvolvedwiththefishermen’smarkets.Thebiggestwaterqualityconsiderationwithfishermen’smarkets(oranyopenairmarket)iswithtrashanddebrisgeneratedbypatronsandvendors,improperdisposalofwaterormeltedice,orimproperwashingoftheusablearea.OrganizersofsuchmarketsareremindedoftheWPOprohibitionoftheseactivitiesandpollutantdischargesfromtheireventsiftheyneedtoobtainaspecialeventpermit.
Microbreweries, Cideries, and Micro‐distilleries
Agriculturalmicrobrewery,cidery,andmicro‐distilleryusescouldincludethefuturedevelopmentofbuildingstosupportstructuresupto5,000squarefeetinsize.Forsmalleroperationsthatproducenomorethan2,000barrelsor62,000gallonsperyear,aministerialpermitcouldbeobtained.Foroperationsupto8,000barrelsand124,000gallonsperyear,adiscretionarypermitwouldberequired.Constructionofanewmicrobrewery,cidery,andmicro‐distilleryfacilitycouldrequiregradingandgrounddisturbance,whichwoulddisturbexistingsoilconditions.Theresultingsoildisturbancecouldincreasethepotentialforerosionandtheamountofsedimententeringstormwaterconveyancesystemsduringastormevent.However,mostconstructionactivitieswouldrequireabuildingorgradingpermitandataminimumwouldtriggertheneedforaMinorSWMP.Similartotheagriculturaltourismactivitiesdiscussedabove,microbreweries,cideries,andmicro‐distillerieswouldalsobeexpectedtoattractvisitorswithincreasedpotentialforpollutantgeneration.
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Mobile Butchering
MobilebutcheringwouldbeallowedundertheproposedprojectbyrightwherePackingandProcessing:LimitedGeneraliscurrentlyallowed.CommercialbutcheringwouldalsoincludeaFoodandBeverageRetailSalesusetype.Mobilebutcheringwouldoperateoutofaself‐containedfacilityandwouldnotinvolveconstructionorgrounddisturbance.Itisanticipatedthatmobilebutcheringcouldproduceasubstantialamountofwastewaterfromwashingprocessedmeat,workareas,andequipment.Statelawpreventsthatwaterfrombeingdischargedtotheground,stormwaterconveyance,orawaterbody.Therefore,operationswouldberequiredtodischargetoasewersystemorcollectedfordisposalataproperfacility.
Wineries
Theproposedprojectwouldallowforanaccessorystructure,upto5,000squarefeettobepermittedforwineries.TheexpansionofwineryusesinS92zonescouldexpandonsitewaterandwastewaterfacilitiesinexistingbuildingsandstructurestoaccommodateadditionalvisitors.Furthermore,wineriescouldrequirenewconstruction,orpromoteground‐disturbingactivitiessuchasgrading,tilling,andplanting,whichcouldpotentiallyresultinanincreaseinpollutants.Similartomicrobreweries,mostconstructionwouldrequirepermitsfromtheCountyandsomeoversightforwaterqualitycontrols.
Summary
Ingeneral,theproposedordinanceamendmentislikelytofacilitateadditionalagriculturalproductionintheCounty.Theseadditionalagriculturaloperationshavethepotentialtocontributepollutantssuchasfertilizers,herbicides,orinsecticidesintosurfacewaterbodies.Pollutantsenteringsurfacewaterbodiesfromagriculturaloperationscouldpotentiallyviolatewaterqualitystandards.Also,somefutureaccessoryoperationscouldoccuralongunpavedruralroads.Dependingonarangeoffactorsincluding,butnotlimitedto,roadconditions,absorptionrates,slope,andthefrequencyanddurationofstormevents,increasedtrafficonunimprovedroadsfromtheadditionofaccessoryoperationscoulddegradethequalityoftheroadsurface.Increasederosionandsedimentationcouldresultinadverseimpactsonsurfacewatersanddrainagesnearunimprovedroads.Contaminantsrelatedtoautomobilesonroadwayscanalsobetransportedinsediments.WhileSWMPsand/orSWPPPswouldoftenbepreparedforsiteswherenewdevelopmentisproposed,theseplansseldomcovertheuseofoffsiteroads.
Insummary,theproposedprojectpromotesanumberofaccessoryagriculturalusesthatmayresultinthegenerationofadditionalpollutantsthroughconstructionactivities,operations,andincreasedvisitation.ThesepollutantsourcesarecommontoruralresidentialandagriculturalpropertiesanddonotposeasubstantiallygreaterrisktotheenvironmentthantheusesthatarealreadyfoundintheunincorporatedareasoftheCounty.Avarietyofregulationsareinplacetoprovideoversightofwaterqualitycontrolsandtoprotectagainstpollutantdischarges.However,evenwiththeseregulations,dischargesofpollutantswouldbeexpectedtooccurbecausesomeactivitieswouldnothaveoversightandBMPsarenotalways100%effectiveateliminatingpollutantdischarges.TheincreaseofaccessoryagriculturalusesintheunincorporatedareasofSanDiegoCountywouldresultinadditionalpollutantdischargesandsuchdischargesmayviolatesurfacewaterqualitystandardsorotherwisesubstantiallydegradewaterquality;therefore,itisconcludedthatimpactsfromtheprojectonsurfacewaterqualitywouldbepotentiallysignificant(ImpactHY‐1).
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2.5.3.2 Soil Erosion
Guidelines for the Determination of Significance
ThefollowingsignificanceguidelinefromAppendixGoftheStateCEQAGuidelinesappliestoboththedirectandcumulativeimpactanalyses.Asignificantimpactwouldoccuriftheproposedprojectwould:
Substantiallyaltertheexistingdrainagepatternofthesiteorarea,includingthroughthealterationofthecourseofastreamorriver,inamannerwhichwouldresultinsubstantialerosionorsiltationon‐oroff‐site.
Analysis
Thenaturalprocessoferosionremovessoil,sediment,androckfromexposedareasandtransportstheresultingsediment.Therateoferosionisdependentonthetypeofmaterialthatiseroded,thetypeandamountoferosiveforces,andtheshapeofthelandforminvolved.Land‐disturbingactivitiesassociatedwiththeconstructionofneworexpandedagricultureoperationsmayresultinthealterationofdrainagepatternsthatcouldcausesubstantialerosionorsiltationonoroffsite.ThepotentialforgradingandconstructiontooccuraspartofaccessoryagriculturalusesisdiscussedaboveunderSection2.5.3.1,WaterQuality.
However,ground‐disturbingactivitiesaresubjecttoCountypermittingrequirementswhenexceedingcertainlimitations.Discretionarygradingpermitsmaybeneededforearthworkinvolving200cubicyardsofsoilimportorexport,orinvolvingmorethan2,500cubicyardsofgrading.ThesepermitstriggeradditionalenvironmentalreviewpursuanttoCEQA.Asmentionedinthesurfacewaterqualitydiscussionabove,issuanceofaGradingPermitisadiscretionaryactionthatrequiresenvironmentalreview.ThesepermitsalsorequireadherencetotheWPOandPartF.3.1oftheStormwaterStandardsManual,whichincludesprovisionsforerosioncontrolBMPs.TheseBMPswouldhelppreventerosion/siltationimpactsensurethaterosion/sedimentationimpactsareavoided.Thus,theproposedordinanceamendmentwouldnotcouldpotentiallyresultinasignificantlyincreaseintheamountoferosionthroughexpandedagricultureoperations.AlthoughsomestructuresmaynottriggertheneedforGradingPermits,BuildingPermitswouldoftenberequiredthatincludeMinorSWMPrequirements.TheGradingandBuildingPermitprocesswouldensurethatapplicantsdemonstratecompliancewithregulationsestablishedintheCountyGradingOrdinancethatprohibit,inpart,anyground‐disturbingactivitiesthatreducethecapacityofawatercourseorimpairtheflowofwaterinawatercourse,andrequireerosionandsedimentcontrols.
Theproposedzoningchangesintheproposedprojectcouldresultinconstructionofnewstructures,parking,landscaping,accessimprovements,andotherfeatureswithinunincorporatedSanDiegoCounty.Newfacilitiescouldresultinpermanentalterationstoexistingdrainagepatternsbyconvertingareasfrompervioussurfacestoimpervioussurfaces.Theseadditionalimpervioussurfacescouldincreaserunoffandpotentiallyresultinnewerosionproblemsortheworseningofexistingerosionproblems.Increasedvehicletripsandmaintenanceactivitiesondirtroadsleadingtotheagriculturaloperationsalsohavethepotentialtoincreaseerosionandsiltation,especiallyduringthewetseasonwhenmuddyconditionsrequireextramaintenancetokeeptheroadsinsatisfactorycondition.FutureagriculturaloperationswouldberequiredbytheWPOtoimplementsitedesignmeasures,sourcecontrol,and/ortreatmentcontrolBMPstoreducepotentialpollutants,includingsedimentfromerosionorsiltation,tothemaximumextentpracticablefromentering
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stormwaterrunoff.TheseBMPsforerosioncontrolareapartoftherequirementforabuildingpermitandareregulatedandenforcedaspartofthebuildinginspectionprocess.Inaddition,theWPOandPartF.4.7.1oftheStormWaterStandardsManualrequirethatallgrading,evengradingthatisexemptfromaGradingPermitrequirement,implementsBMPstoavoidimpacts.CompliancewiththeWPOandPartF.4andPartF.4.7.1oftheStormWaterStandardsManualwillensurethatdevelopmentoffacilitieswouldnotresultinsubstantialerosionorsiltationonsite.
FutureprojectsthatinvolvestructureslargerthantheallowablebyrightsizeundertheZoningOrdinancewouldrequireapermitandbesubjecttotheWPO,includingpreparationofaSWPPPandsite‐specificBMPsandLIDtechniquestoreduceimpactsonwaterquality.Aswiththeexpansionofagriculturaloperations,shouldtheconstructionofnewstructuresandtastingroomsrequireclearingorgradingthatexceeds200cubicyards,adiscretionaryGradingand/orAdministrativePermitforclearingwouldberequired.TheseactivitieswouldbesubjecttotheNPDESconstructionstormwatergeneralpermitprogram,whichrequiresaSWPPPtobepreparedandBMPstobeidentifiedforconstructionsitesgreaterthan1acre.TheimplementationofappropriateBMPswouldreduceerosionbyminimizingsitedisturbanceandcontrollinginternalconstructionerosion.
Muchlikethewaterqualitydiscussion(Section2.5.3.1above),thereareseverallayersofprotectionavailablethatwouldhelppreventerosion/siltationimpacts,suchastheBMPsrequiredinconjunctionwithabuildingpermit,GradingPermit,orAdministrativePermitforground‐disturbingactivities.However,aswithwaterquality,evenwithalltheseregulationsitisimpossibletoprovideoversightofallactivitiesandtoensureadequacyofallBMPs.Therefore,impactsrelatedtosubstantialerosionorsiltationfromagriculturaloperationswouldbepotentiallysignificant(ImpactHY‐2).
2.5.3.3 Drainage
Guidelines for the Determination of Significance
ThefollowingsignificanceguidelinefromAppendixGoftheStateCEQAGuidelinesappliestoboththedirectandcumulativeimpactanalyses.Significantimpactswouldoccuriftheproposedprojectwould:
Createorcontributerunoffwaterthatwouldexceedthecapacityofexistingorplannedstormwaterdrainagesystems.
Analysis
Constructionofimpervioussurfaces,suchashorsestables,buildings,parkinglots,anddriveways,reducestheamountofrainfallthatcaninfiltratethegroundsurfaceandmovetothesubsurface.Asaresult,thevolumeofsurfacewaterrunoffincreaseswithinawatershed;subsequently,artificialconveyancessuchasgutters,stormpipes,andnaturalchannelimprovementstoaccommodateadditionalvolumeacceleratetherateofflowofwaterinthewatershed.Thisfaster‐moving,highervolumeofsurfacewaterrunoffwithinawatershedresultsinahigherprobabilityandincreasedseverityoffloodingwithinawatershedifdrainagefacilitiesarenotadequatelymaintainedorconstructedtocarrypeakflowcapacity.Accessoryagriculturalusesmayresultinthedevelopmentofimpervioussurfaces,suchasstorageareas,buildings,parkinglots,anddrivewaysthatcouldaffectexistingorplannedstormwaterdrainagesystems.
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Ifafutureaccessoryuserequiresthebuildingorremovalofastructure,abuildingpermitwouldberequired,anddevelopmentofthefacilitywouldbesubjecttothepreparationofaMinorSWMPandsite‐specificBMPsandLIDtechniquestomaintainexistingdrainagepatternsandrunofflevelstothegreatestextentpossible.ConformancetotheWPOandotherlocalrequirementswouldensurethatfuturefacilitiesdonotsubstantiallyaltertheexistingdrainagepatternsorcontributerunoffwaterthatwouldpotentiallyexceedthecapacityofexistingorplannedstormwaterdrainagesystems.
ProjectstriggeringGradingPermitsorotherdiscretionaryapprovalswouldbeevaluatedunderCEQAandwouldberequiredtoimplementmeasurestominimizealterationstoexistingdrainagepatterns,asnecessary.CEQArequiresproposedprojectstoprovidedetailedinformationonthepotentiallysignificantenvironmentaleffectstheyarelikelytohave,listwaysinwhichthesignificantenvironmentaleffectswouldbeminimized,possiblyidentifyalternativesthatwouldreduceoravoidthesignificantimpactsidentifiedfortheproject,andproposemitigationforsignificantimpacts.
Thediscretionaryreviewprocessrequiresthesubmittalofpre‐andpost‐constructiondrainageinformationtoensurethatprojectsdonotsubstantiallyalterdrainagepatternsandincreaserunoff.TheCountymayalsorequirethepreparationofaDrainageReportinaccordancewiththeCountyHydrologyManual,whichprovidesuniformproceduresforstormwateranalysis(CountyofSanDiego2003a).PrioritydevelopmentprojectsarealsosubjecttotheCountyHydromodificationManagementPlan.Althoughfocusedonerosionprotection,hydromodificationcontrolmeasuresalsoassistinthemanagementofrunoffvolumesandrates.Theselocalregulationsensurethatprojectsaredesignedtomeetthecapacityofexistingstormwatersystems,orarerequiredtoretrofitstormwaterdrainagesystemssothattheywouldnotcauseflooding.
Becauseofthelevelofoversightprovidedbyexistingregulationswhenthereareadditionalimperviousareas,theproposedprojectwouldnotresultinsignificantimpactsrelatedtoexceedingthecapacityofstormwatersystems.
2.5.4 Cumulative Impacts Analysis
Thegeographicscopeofcumulativeimpactanalysisvariesdependingonthetypeofresourcewithpotentialtobeaffected.Hydrologyandwaterqualityonacumulativelevelincludeallagriculturaloperationsthatmaycontributerunofforpollutants,ormayotherwisedegradewaterresourcesintheCounty.Developmentofrelatedagriculturaloperationsthatinvolvesoildisturbanceandtheadditionofimpervioussurfacesthatcouldleadtochangesinsoilerosionanddrainagepatternsarealsoincluded.However,thepotentialforcombiningimpactsislimitedtowatersheds.Assuch,thegeographicscopeforthecumulativeanalysisincludesthosewatershedsthatcovertheunincorporatedareas,includingtheportionsofthewatershedsthatincludesurroundingcitiesandcounties.
2.5.4.1 Surface Water Quality
Overallwaterqualityintheregionhasdegradedovertimeasnaturalhabitathasbeenconvertedanddevelopedforotheruses,andtheseuseshaveresultedinrunoffofvariouspollutantsintoregionalsurfacewaterbodiesandtheirtributaries.Avarietyofprogramshavebeenimplementedwiththegoalofhaltingdegradationofwaterqualityandreversingthistrend.Severalstateandfederalagenciesareinvolvedintheseprograms,manyofwhichcomefromthefederalCWA.Nonetheless,acumulativeadversewaterqualityconditionexists.
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Constructionoftheproposedprojectaswellasconstructionoftherelatedprojectswouldresultinsurfacedisturbancethroughgroundscraping,grading,trenching,andcompactionassociatedwithtypicaldevelopmentactivities.Insomecases,existingvegetationwouldberemoved,therebyincreasingthepotentialforerosion.Operationalactivitiesandproposedlanduses(e.g.,crops,parkingareas)wouldgeneratecontaminantdischarges,suchasfertilizers,pesticides,petroleumproducts,andvolatileorganiccompounds,whichwouldbecarriedinstormwaterrunoff.Theseconstituentscouldenterthestormdrainagesystemandadverselyaffectwaterquality.Althoughavarietyofregulationsareinplacetoreducepollutantdischarges,somedischargesareexpectedtooccur.Whenthepotentiallysignificantproject‐levelimpactonsurfacewaterquality(ImpactHY‐1)isconsideredatthecumulativelevel,theproject’scontributiontoacumulativeimpactisconsideredtoalsobepotentiallysignificant(ImpactHY‐3).
2.5.4.2 Soil Erosion
TheWPOandtheStormWaterStandardsManualrequirethatallgradingmustimplementBMPstoavoidimpactsfromerosionorsiltationonsite.Thisensuresthatallfuturedevelopmentisrequiredtocomplywithmeasuresthatreducecumulativeimpactsfromerosionorsiltationtoaless‐than‐significantlevel.
Futuredevelopment,whencombinedwithfutureagricultureprojects,couldincreasetrafficonunimprovedroads,andthesedimentationanderosionthatcouldresultmightcontributetosurfacewaterqualityimpactsthatmightexceedtheBasinPlan’swaterqualityobjectiveforsedimentinsomelocations;therefore,theseindirectandoffsiteimpactscouldcausesurfacewaterqualityimpactsthatwouldbecumulativelyconsiderable.FutureagricultureprojectswouldbeexpectedtofollowregulationssuchasNPDESorothersapplicable.Proposedaccessoryagriculturaloperationsthatdonotrequirediscretionaryreviewmaystillrequireabuildingpermitifanystructuresareproposedtobeconstructedordemolished,andthereforewouldbesubjecttopreparationofaMinorSWMP,whichincludesrequirementsforconstructionBMPs,LID,andpost‐constructionBMPs.However,evenwithseverallayersofprotectionavailabletohelppreventerosion/siltationimpacts,suchastheBMPsrequiredinconjunctionwithvariouspermitsforground‐disturbingactivities,theproject‐levelimpactrelatedtosubstantialerosionorsiltationfromagriculturaloperationsispotentiallysignificant.Whenthepotentiallysignificantproject‐levelimpactonsoilerosion(ImpactHY‐2)isconsideredatthecumulativelevel,theproject’scontributiontoacumulativeimpactisconsideredtobepotentiallysignificant(ImpactHY‐4).
2.5.4.3 Drainage
Developmentoftheproposedprojectincombinationwithdevelopmentoftherelatedprojectswouldresultintheadditionofimpervioussurfaces,whichcouldincreasestormwaterrunoff.However,inaccordancewithfederalandstatestormwaterregulations,newconstructionandsignificantredevelopmentmustmaintainpre‐projecthydrologyandincorporateproperpollutantsourcecontrols,minimizepollutantexposureoutdoors,andtreatstormwaterrunoffthroughproperpost‐constructionBMPswhensourcecontrolorexposureprotectionareinsufficientforreducingpollutantloads.Therefore,beforeanyconstruction‐relatedgrounddisturbance,finaldrainageplanswouldberequiredtodemonstratethatallrunoffwouldbeappropriatelyconveyedandnotleavetheprojectsitesatratesexceedingpre‐projectrunoffconditions.Consequently,theproposedprojectwouldnothaveaconsiderablecontributiontocumulativedrainageimpactssuchthatanewcumulativeimpactwouldoccur.Thiswouldbealess‐than‐significantcumulativeimpact.
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2.5.5 Significance of Impacts Prior to Mitigation
Theproposedprojectwouldresultinpotentiallysignificantimpactsassociatedwithhydrologyandwaterresourcesinvolvingwaterquality,includingsurfacewaterquality(ImpactsHY‐1,direct/indirect,andHY‐3,cumulative)andsoilerosion(ImpactsHY‐2,direct/indirect,andHY‐4,cumulative).Theproposedprojectwouldnotresultinpotentiallysignificantimpactsondrainagerelatedtoexceedanceofstormwatersystemscapacity.
2.5.6 Mitigation Measures
Theproposedprojectwouldallowfordevelopmentofaccessoryusestoagriculturallands.Futuredevelopmentfosteredbytheproposedproject,suchasagriculturalandhorticultureretail(large),agriculturalmicrobreweries,cideries,andmicro‐distilleries(large),andanimalraisingwouldberequiredtoobtainadiscretionarypermit,whichwouldtriggerdiscretionaryenvironmentalreviewandfeasiblemitigationwouldbeproposed.Typicalmitigationmeasuresfortheseprojectscouldincluderequirementsforprojectapplicantsto:demonstratewastedischargerequirementshavebeenmetinaccordancewithRWQCBNPDESpermitconditions;implementprojectdesignmeasuressuchasconstructionstormwaterBMPsforerosionandsedimentcontrol,roadimprovementandpaving,runoffcatchment,andfiltration;andlimituseoftoxiccompounds(fertilizersandpesticides)tominimizeimpacts.Asaresult,specificimpactsonwaterqualitywouldbeanalyzedandmitigatedforthesetypesofdiscretionaryprojects.
Atthesametime,theremayalsobefutureby‐rightprojectsforwhichrelateddiscretionarypermitsarerequiredbutforwhichmitigationwouldnotbefeasible,orforwhichnorelateddiscretionarypermitisrequired(e.g.,wheregradingisallowedundertheby‐rightuse,butwhichwouldimpactnativeorfallowland).Forsuchby‐rightprojects,CEQAreviewwouldnotberequired,andappropriatemitigationwouldnotbepossible.
Additionally,thefollowingfeasiblemitigationmeasureswouldapplytofutureprojectsundertheAgriculturePromotionProjectthatwouldberequiredtoundergoenvironmentalreview.Asitcannotbeconcludedatthisstagethatimpactsonwaterqualityfromallfutureagriculturalprojectsallowedbytheordinanceamendmentwouldbeavoidedormitigated,impactswouldremainsignificantandunmitigated.
2.5.6.1 Water Quality
Theproposedprojectwouldamendcurrentregulationsrelatedtoaccessoryagriculturalprojectsthatmaydirectlyorindirectlyresultinaviolationofwaterqualitystandardsorwastedischargerequirements,orotherwisesubstantiallydegradewaterquality(ImpactsHY‐1,direct/indirectandHY‐3,cumulative).Mitigationmeasuresdescribedbelowhavebeenidentifiedthatwouldreducewaterqualityimpactsduringconstructionandoperation,butnotbelowasignificantlevel.Therefore,theseimpactswouldremainsignificantandunavoidable.Chapter4,ProjectAlternatives,providesadiscussionofalternativestotheproposedprojectthatwouldresultinsomereducedimpactsassociatedwithwaterqualityascomparedtotheproposedproject.
Mitigation Measures
M‐HY‐1:Duringtheenvironmentalreviewprocessforfuturediscretionarypermitsforaccessoryagriculturaluses,theCountyGuidelinesforDeterminingSignificanceforHydrology
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andWaterQualityResourcesshallbeapplied.Whenimpactsonhydrologyaredeterminedtobesignificant,feasibleandappropriateproject‐specificmitigationmeasuresshallbeincorporated.
M‐HY‐2:ComplywiththeNPDES,RWQCB’sConditionalWaivers,CountyofSanDiegoWPO,andtheCountyGradingOrdinance,requirepreparationofstormwatermanagementplansasapplicable,andimplementBMPs.
2.5.6.2 Soil Erosion
Theproposedprojectwouldamendcurrentregulationsrelatedtoaccessoryagriculturalprojectsthatmaydirectlyorindirectlyresultinsoilerosionimpacts(ImpactsHY‐2,direct/indirect,andHY‐4,cumulative).MitigationmeasuresM‐HY‐1andM‐HY‐2wouldreducesoilerosionimpactsduringconstructionandoperation,butnotbelowasignificantlevel.Therefore,theseimpactswouldremainsignificantandunavoidable.Chapter4,ProjectAlternatives,providesadiscussionofalternativestotheproposedprojectthatwouldresultinsomereducedimpactsassociatedwithsoilerosionascomparedtotheproposedproject.
2.5.7 Conclusion
Becausefuturedevelopmentofanunknownnumberofneworexpandedagriculturaloperationsatunknownlocationscouldcauseimpactstosurfacewaterqualityanderosion/siltation,adoptionoftheproposedordinanceamendmentcouldresultinpotentiallysignificantdirect,indirect,andcumulativeimpacts(ImpactsHY‐1,HY‐2,HY‐3,andHY‐4).By‐rightuseswouldnotbesubjecttodiscretionaryapproval,and,thus,noadditionalenvironmentalreviewwouldbeconducted.Therefore,theseimpactsaresignificantandunmitigatedbecausetherewouldbenoenforcementmechanismtoguaranteeavoidanceorcompliancewithenvironmentalregulations.CompliancewithallapplicableregulationsincludingtheWPOandGradingOrdinancewouldensurethatdrainageimpactsareaddressedandarelessthansignificant.
Table 2.5‐1. Criteria for Rating Soil Erodibility
SoilPropertiesAffectingErodibility
Erodibility
Slight Moderatea Severeb,c
SurfaceLayerTexture(sedimentcomposition)c
Clay Clayloam,sandyloams,loam
Sands,orloamysands
Gradeofgranular,crumb,orblockystructureinthesurfacelayer(particlesizeandstrength)
Strong Moderate Weakandmassiveandsinglegrain
Depthtomaterialthatrestrictspermeability
Morethan40inches 20–40inches Lessthan20inches
Slope Lessthan15% 15–30% Morethan30%
Source:Table12fromU.S.DepartmentofAgriculture’sSoilSurveyfortheSanDiegoAreaPartII;CountyofSanDiego2007e.aRatingisslightforclayloam,sandyloams,loam,sands,andloamysandsifcoarsefragmentscovermorethan75%ofsurface.bRatingismoderateforsandsandloamysandsifcoarsefragmentscover25to75%ofsurface.cRatingisaccordingtosurfacelayertextureifcoarsefragmentscoveronly1to25%ofsurface.