section 2.5 hydrology and water quality · draft final environmental impact report agriculture...

Draft Final Environmental Impact Report

Agriculture Promotion Project 2.5‐1

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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,

County of San Diego Section 2.5. Hydrology and Water Quality



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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

County of San Diego Agriculture Promotion Program

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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.




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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




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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.




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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




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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.




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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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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


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).


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.


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.

section 2.5 hydrology and water quality · draft final environmental impact report agriculture...

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