final ou2 baseline ecological risk assessment report. · ou2 ecological risk assessment report ......

FINAL OU2 Baseline Ecological Risk Assessment Report

Formosa Mine Superfund Site Douglas County, Oregon

R10 AES (SMALL BUSINESS) CONTRACT NO. 68S70304

Task Order No. 047B

Prepared for: U.S. Environmental Protection Agency

Region 10 1200 Sixth Avenue, Suite 900 Seattle, Washington 98101

Prepared by: CDM Federal Programs

1218 Third Avenue, Suite 1100 Seattle, Washington 98101

Parametrix 411 108th Avenue NE, Suite 100 Bellevue, Washington 98004

July 11, 2014

FINAL

OU2 Baseline Ecological Risk Assessment Formosa Mine Superfund Site

Douglas County, Oregon

Tony C. Gendusa Ph.D. CDMSmith Ecological Toxicologist

QA ReviawbY!( Kim Ziiis CDM Smith QA Officer

~woved by: Michael C. Allen CDM Smith Project Manager

R-10 AES (SMALL BUSINESS) CONTRACT NO. 68-S703-04

Task Order No. 047B

cfv/7 /P,;l.~lf Date

~ 10 z,,,,j Date

Signature Page

Thispageintentionally leftblank

ii

Table of Contents

Section 1 Introduction ................................................................................................................................. 11 1.1 PurposeandApproach ............................................................................................................................................11

1.2 SiteDescription...........................................................................................................................................................12

1.3 ContaminantSources ...............................................................................................................................................13

1.3.1 SurfaceWater...............................................................................................................................................13 1.3.2 Groundwater ................................................................................................................................................13

1.4 EcologicalInvestigations........................................................................................................................................14

1.5 OrganizationofthisReport ...................................................................................................................................14

Section 2 BERA Problem Formulation.................................................................................................... 21 2.1 StressorIdentification .............................................................................................................................................21

2.1.1 ChemicalsandExposureMediaofPotentialConcern................................................................22 2.1.2 RefinementofChemicals ofPotentialConcern.............................................................................22 2.1.3 SummaryofExposureAreas.................................................................................................................22

2.2 EcologicalResourcesatRisk.................................................................................................................................23

2.2.1 Habitats...........................................................................................................................................................23

2.2.1.1 AquaticHabitats..........................................................................................................................23 2.2.1.2 Fateand TransportwithinAquaticHabitats..................................................................27 2.2.1.3 TerrestrialHabitats....................................................................................................................27 2.2.1.4 Fateand TransportwithinTerrestrialHabitats............................................................28

2.2.2 EcologicalReceptors .................................................................................................................................28

2.2.2.1 AquaticReceptors.......................................................................................................................28 2.2.2.2 TerrestrialReceptors................................................................................................................29 2.2.2.3 FederallyListedSpecies........................................................................................................ 210

2.3 EndpointsandRiskQuestions/Hypotheses................................................................................................ 211

2.3.1 Objectivesand AssessmentEndpoints .......................................................................................... 211

2.3.1.1 SurfaceWaterBasedAssessmentEndpoints .............................................................. 212 2.3.2 MeasurementEndpoints......................................................................................................................212 2.3.3 RiskQuestions/Hypotheses................................................................................................................ 213

2.4 ConceptualSiteModel .......................................................................................................................................... 214 Section 3 BERA Exposure Assessment.................................................................................................... 31

3.1 ExposureMedia ..........................................................................................................................................................31

3.2 ExposureAreas ...........................................................................................................................................................31

3.3 DataUsedintheBERA.............................................................................................................................................31

3.4 WaterQuality Parameters .....................................................................................................................................32

3.5 ScreeningofChemicalsofPotentialConcern................................................................................................33

3.5.1 SurfaceWaterExposurePointConcentrations.............................................................................33 3.5.2 EcologicalScreeningLevels...................................................................................................................34 3.5.3 ChemicalScreeningandSelectionofFinalCOPCs.......................................................................34

3.6 ContaminantFateand Transport........................................................................................................................35 3.6.1 EnvironmentalPersistence....................................................................................................................35 3.6.2 Bioconcentration Potential ....................................................................................................................35

3.6.2.1 EvaluationofMercuryasaCOPC.........................................................................................36 3.6.3 Bioavailability ..............................................................................................................................................38

3.7 ExposureofEcologicalReceptors.......................................................................................................................39

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Table of Contents

3.8 UncertaintyAnalysis..............................................................................................................................................310 Section 4 BERA Effects Assessment ..........................................................................................................41

4.1 ToxicityReferenceValues...................................................................................................................................... 41

4.2 UncertaintyAnalysis................................................................................................................................................ 43

Section 5 BERA Risk Characterization.....................................................................................................51 5.1 RisksBasedonDirectExposure ......................................................................................................................... 51

5.1.1 RiskstoAquaticLife.................................................................................................................................. 52

5.1.1.1 RisksBasedonSurfaceWaterCOPCConcentrations.................................................52

5.1.2 RisktoUpperTrophicLevelReceptors............................................................................................ 54

5.2 OtherSupportingData ............................................................................................................................................ 54

5.2.1 FishCommunityData............................................................................................................................... 54

5.2.1.1 HistoricalData.............................................................................................................................. 54

5.2.1.2 RecentData.................................................................................................................................... 55

5.2.2 BenthicMacroinvertebrateCommunityData ............................................................................... 57

5.2.2.1 HistoricalData.............................................................................................................................. 57

5.2.2.2 RecentData.................................................................................................................................... 58

5.3 RiskSummary ...........................................................................................................................................................514

5.3.1 RisktoAquaticandWaterDependentReceptors.....................................................................514 5.3.2 ResponsestoRiskQuestions ..............................................................................................................514 5.3.3 SpatialExtent ofImpairment..............................................................................................................515 5.3.4 SummaryofRiskstoAquatic Life.....................................................................................................516

5.4 UncertaintyAnalysis..............................................................................................................................................518

5.5 EcologicalIssuesRelatingto RemedialAlternatives...............................................................................519

5.6 ConclusionsoftheOU2BERA ............................................................................................................................520

5.6.1 EvaluationofApril2014 SurfaceWaterData .............................................................................520 5.6.2 EvaluationofBioticLigandModel....................................................................................................520

Section 6 References .....................................................................................................................................61

List of Tables Table 11 Sampling Locations and DatesforSurfaceWaterSamples Table21 Wildlife and Plants Found atthe Formosa MineOU2and VicinityTable22 Federally Listed,Candidate Species,and Speciesof Concernand Potential to Occur

atthe Formosa MineOU2andVicinityTable23 RelationshipbetweenEndpointsandRiskQuestionsfor the Formosa MineOU2

BERATable31 StatisticalSummaryfor SurfaceWater AnalyticalDissolvedResults and Selection

of Chemicals of Concern Table32 Summaryof WaterQuality ParametersbasedonFieldSampling Table33 Summaryof Chemicals of PotentialConcern Table34 Summaryof MercuryAnalytical ResultsTable41 Summaryof Aquatic LifeScreening Criteria Table42 HardnessandSulfate AdjustedSurfaceWaterToxicity ReferenceValues,Middle

CreekTable43 HardnessandSulfate AdjustedSurfaceWaterToxicity ReferenceValues,South

Fork MiddleCreek

iv

Table of Contents

List of Tables (continued) Table44 HardnessandSulfate AdjustedSurfaceWaterToxicity ReferenceValues,Middle

Creek Reference Table45 HardnessandSulfate AdjustedSurfaceWaterToxicity ReferenceValues,South

Fork MiddleCreek Reference Table46 Summaryof ChronicSurfaceWaterToxicityReferenceValues Hardness

Adjusted byExposureArea Table51 ChronicHazardQuotients byLocation for FishinMiddleCreek Table52 ChronicHazardQuotients byLocation for FishinSouthFork MiddleCreekTable53 SalmonidSpecific HazardQuotients Table54 TotalNumberofFishObservedduring Historical andRecent Surveys Table55 PredictiveModeling Scores and ConditionsBased onBMIData Table56 TotalNumberofBMITaxa atMiddleCreekSamplingLocations Table57 TotalNumberofEPTTaxa atMiddleCreekSamplingLocations Table58 TotalNumberofBMITaxa at South ForkMiddle Creek Sampling Locations Table59 TotalNumberofEPTTaxa at SouthForkMiddleCreek Sampling Locations Table510 Total NumberofBMITaxa at Reference Sampling Locations Table511 Total NumberofEPTTaxa at Reference Sampling Locations Table512 Habitat Characteristicsof theEcologicalSamplingLocations Table513 ToxicityValuesPotentialTRVs forSurface WaterCOPCsBasedon Protection of

SalmonidFishandBMI Table514 ChronicHazardQuotients by Location for FishinMiddleCreek Table515 Chronic HazardQuotients by Location for FishinShouldFork MiddleCreek

List of Figures Figure11a Ecological Sampling Locations Figure11b Ecological Sampling Locations Figure 11c Ecological Sampling Locations Figure21 OU2Exposure Model for Human and Ecological Receptors Figure51 Total NumberofBMIOrganismsinMiddle CreekandReference Locations Figure52 Total NumberofBMIOrganisms in South Fork Middle Creek andReference

Locations Figure 53 Total Numberof BMITaxain Middle Creek and ReferenceLocations Figure54 Total NumberofBMITaxain South Fork MiddleCreek and Reference Locations Figure55 Numberof EPT Taxain MiddleCreek andReferenceLocations Figure56 Numberof EPTTaxainSouthFork Middle Creek and Reference Locations Figure57 Concentrationsof DissolvedMetalsandBMIMetricswhereSampledConcurrently Figure58a Impairment ofStreamsbasedon BMICondition Scores and EcologicalRiskHQs Figure58b Impairment ofStreamsbasedon BMICondition Scores and EcologicalRiskHQs Figure58c Impairment ofStreamsbasedon BMICondition Scores and EcologicalRiskHQs

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Table of Contents

List of Appendices AppendixA Surface WaterAnalyticalDataResults and FieldMeasurements AppendixB SiteSpecific HardnessCalculations Appendix C Evaluationof AcuteRisk AppendixD BenthicMacroinvertebrate Datafrom the BLM/USU NationalAquaticMonitoring

Center

vi

CCC

Acronyms % percent ARD acid rock drainage BERA baseline ecological risk assessment BLM Bureau of Land Management BMI benthic macroinvertebrate CaCO3 calcium carbonate

Criterion Continuous Concentration CF conversion factor COI chemical of interest COPC chemical of potential concern CSM conceptual site model CVAAS cold vapor atomic absorption spectrometry DO dissolved oxygen DOGAMI Oregon Department of Geology and Mineral Industries EA exposure area EPA United States Environmental Protection Agency EPC exposure point concentration EPT Ephemeroptera, Plecoptera, Trichoptera ERA ecological risk assessment ESL ecological screening level FS feasibility study HQ hazard quotient mg/kg milligrams per kilogram mg CaCo3/L milligrams of calcium carbonate per liter MIW mining influenced water MREF Middle Creek Reference location NMFS National Marine Fisheries Service NRWQC National Recommended Water Quality Criteria OAR Oregon Administrative Rules O/E observed to expected ODEQ Oregon Department of Environmental Quality ODFW Oregon Department of Fish and Wildlife OU Operable Unit PREDATOR Predictive Assessment Tool for Oregon PRGs preliminary remediation goals RI/FS remedial investigation/feasibility study SFREF South Fork Middle Creek Reference location SLERA screening level ERA TRVs toxicity reference values UCL upper confidence limit g/L micrograms per liter S/cm microsiemens per centimeter USFWS U.S. Fish and Wildlife Service USGS United States Geological Survey

vii

Table of Contents


viii

Section 1 Introduction Aspartoftheremedialinvestigationandfeasibilitystudy(RI/FS)forFormosaMine OperableUnit2(OU2),UnitedStatesEnvironmentalProtectionAgency(EPA)isconductingabaseline ecologicalriskassessment(BERA).EvaluationsintheOU2BERAassesspotential threatstotheenvironmentthatmayexistresultingfromthereleaseorthreatenedreleaseofcontaminantsat or fromOU2if no remedialactionis taken.Conclusions(Section5.6) oftheOU2 BERA will beintegratedintothe futureOU2RIreport,which will bepreparedinboth draftandfinal versions.TheDraftRIfor OU2willinclude an evaluation of groundwaterandsurfacewaterdatacollectedfromOctober2009throughApril2014. TheFinalRIforOU2 isscheduledtoincorporateinformationfromtheFormosaAditremovalactionbeingconducted in2015 bytheBureauofLand Management(BLM)thatis designedto containminepoolwaterwithin adit.Intheinterim,datawill becollectedtoassesstheeffectstosurfaceandgroundwaterresulting from sealing theFormosa1Adit.EPAanticipates atleast threetofiveyearsfor waterwithinthemine pooltoreachequilibrium with the new hydraulic conditions beforeeffects wouldbeseenin downgradientsurfacewater. OU2includes surfacewater,sediment,groundwater,underground workings, and adit water drainageassociatedwiththeFormosaMine.Itexcludesthesurfaceandsubsurface minewastes (tailings andwasterock)andsoils thatweredepositedoutsideofthemine workings,representedbyOU1andevaluatedas partoftheOU1RI/FS (CDM2012 andCDMSmith2013).Seethe OU1RIandFSdocumentsforinformationonpreviousinvestigations conducted attheFormosaMineSitesince1988. TheOU2BERAisbased onanevaluationofsurfacewaterdata,whereas theOU2RI will includean evaluationof groundwater andwill includea human healthrisk evaluation. TheOU1ecologicalriskassessments(ERA)werereportedinthe OU1RI(CDM2012) toquantifycurrentorpotentialthreats toecologicalreceptorsfromenvironmentalcontaminantsintheabsenceofanyremediationandto helpdeterminewhetherremedialactionsarewarranted.TheOU1ERAfocusedonterrestrialhabitatsandreceptorspotentiallyassociatedwith theformerminesite.The OU1ERAincludeda screeninglevelERA (SLERA)for aquaticenvironmentsadjacenttotheFormosa Minesite. The SLERAevaluationwas basedoncomparisonsofdissolvedconcentrationsofselectedmetalsinsurfacewaterat seepandstreamlocations intheheadwatersofMiddleCreekandSouthForkMiddleCreektosurfacewaterecologicalscreeninglevels (ESLs).Dissolved metalsconcentrations,whicharethemosttoxicform,werecomparedto chronicNationalRecommended WaterQualityCriteria(NRWQC)establishedby EPA fortheprotectionof aquaticlife.TheSLERAidentifiedseveralchemicalsofpotentialconcern(COPCs)fortheaquaticecosystems.Basedonthesefindings,aBERAwasrecommended for OU2.ThisdocumentpresentstheOU2BERA.

1.1 Purpose and ApproachERAsareperformedtodetermine ifecologicalreceptorsareat risk fromexposuretositerelatedcontamination.ERAsaremostoftenconductedusing a phasedapproachthat followsEPAguidancefor conducting ERAsat Superfundsites.The approachusedtoconductthisERAfollows Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments(EPA1997). ItisgenerallyrecognizedbyEPA(1997) andothers thatthosemethodsforconducting

11

Section 1 Introduction

ERAsmustbesitespecific.TheEPAguidance(1997)isthereforenotadetailedstepbystep"cookbook" butinsteadprovidesrecommendationsonERA componentstobeconsideredandgeneralapproachesforperforming ERAs.As muchaspracticable,themethods,recommendations,and terminologyofthe1997 EPAguidanceareusedtoconducttheOU2BERA. ThefirstphaseoftheERA isa SLERA.TheSLERA is usedtodetermine iffurtherinvestigationiswarrantedbasedonareasonablepotentialforecologicalreceptors tosufferadverseeffectsas aresultofexposuretositerelated contamination.If theSLERAdeterminesthatadverseeffectsare likely,thenthenextphaseoftheERAprocessiswarranted.Thissecondphase istheOU2BERA.Whereindicated bytheresultsofthe SLERA, the BERAisperformedto describe ecologicalrisksandtoreducetheuncertainties associated with conservativeriskestimationsin theSLERA. As the initial step for ecological evaluations, a SLERAwas conductedasa componentofthe OU1RI(CDM2012). TheSLERAincludedan evaluationofselected,potentiallysiterelatedmetals(cadmium,copper,lead, nickel,and zinc)insurfacewaterinthe upperreaches ofMiddleCreekandSouthForkMiddleCreek.BasedontheresultsoftheSLERA,cadmium,copper,andzincwereidentifiedasCOPCsforaquaticecosystemsinOU2,andaBERAwasrecommendedtoevaluatefurthertherisktoecologicalreceptorsinOU2. TheOU2BERArefinestheconservativeassumptionsusedintheSLERAtoprovidemoreconfidentestimationsof risk,provide informationthatcanhelp establishremedialpriorities,andservesasa scientificbasis forregulatory andremedialactionsfor thesite.TheOU2BERAis basedonanapproach usingmultiple linesof evidence whilethe SLERAtakes a morestreamlinedapproachtoestimaterisks. Aprimaryline ofevidenceforboththe SLERAandtheBERA isa comparisonofcontaminantconcentrationsin sitesurfacemedia(e.g.,surfacesoil)toconcentrationsassociatedwithadverseeffects.Following EPAguidance, theSLERAconservativelycomparesmaximumconcentrationsofcontaminantsmeasuredinvarious mediatoconservativebenchmarkconcentrations,primarilythosetermedESLs.TheOU2BERAdiffers fromthisconservativeapproachbygenerallyassessinga range, e.g.,themean andmaximum,ora morerealisticandreasonable upperlevelpointestimate,e.g.,upper95thpercent(%)confidencelimitofthearithmeticmean(95% upperconfidencelimits[UCL])ofmeasuredcontaminantconcentrations.Theseexposureconcentrationsarethencomparedtolessconservativeeffectsconcentrations(termedtoxicityreference valuesorTRVs) that,totheextentpossible,aredirectly relevanttositespecificreceptorsand exposurescenarios. IntheBERA,theseprimarylinesofevidencearesupplementedbyotherssuchas foodwebmodeling,siteobservations,biologicalsurveys,ortoxicity testing.Finally,additionalevaluations or investigationsmaybe performedattheFSstageoftheRI/FSprocessthat furtherrefineinformationpresentedintheBERA tospecificallyaddressremedialdesignneeds.

1.2 Site DescriptionTheFormosaMine,locatedinsouthwestOregoninDouglasCounty, iswithin theCoast Range KlamathMountainsatelevationsbetween3,200and3,700feet abovemean sealevel.Thearea isheavilyforestedand consistsofupland, riparian, and aquatichabitats.ThefourmajorwatershedsinthevicinityincludeUpperMiddleCreekandSouthForkMiddleCreek,whichareperennialstreamsthataretributariestoMiddleCreek,andRussellCreekandWestForkCanyonCreek.TheUpper MiddleCreekandSouthForkMiddleCreek watershedsare theprimarysurfacewater drainagesintheareaof interestfortheOU2BERA.Based onsurfacewater sampling,RussellCreekandWestForkCanyonCreek,north andeastoftheFormosaMine,respectively,arenotaffectedbythemine.

12


1.3 Contaminant Sources The primary contaminantsources are minematerials that contain sulfideminerals.Exposureoftheseminematerialstoprecipitationandoxygenresultsinsulfideoxidationandsubsequentrelease ofdissolvedmetalsandmetalloids to theenvironment. Thisprocessisreferredtoasacidrockdrainage(ARD) and isthe dominant contaminantreleasemechanism.Thegeneraltermmininginfluencedwater(MIW)isusedtodescribe ARDonceittransportsfromthe generationsource. Mining was conductedprimarilyby undergroundmethods,whichresultedinconstructionofanetworkofundergroundvoids,partialbackfillofundergroundvoidswith ARD generatingminematerials,andplacementofARD generating mine materialsonthesurface.Reclamationofthemine between1993and1995 includedremovalofformer mineralprocessingfacilities,haulageoflow gradeoreandtailings intotheunderground mine, regrading of waste rock and other minematerialslocatedonthesurface,constructionofa tailingsrepositoryinaformerwaterstoragepond(theencapsulationmound),andrevegetation. 1.3.1 Surface Water Surfacewatersamplinghas beenconductedtoassesseffectsof theMIWdischarge onsurfacewater,examine contaminant transport pathways, and evaluate the downstream extentofeffectstosurface waterquality. Table 11 providesasummaryofmeasurementstakenbyeventandlocation.SamplingeventsfromOctober2009throughJanuary2011arereportedintheOU1RIdocument.WatermeasurementsfromOctober2009throughApril2014areincluded in theOU2 RIreport.The FinalOU2RIreportwilldocumentall waterdataincludingpostremoval action monitoring data. Basedonthesedata,surfacewaterqualityinbothMiddleCreek andSouthForkMiddleCreekisaffectedbyMIW.Aprimarysourceofcontaminantsin surfacewatersisMIWdischargesfrom groundwater tosurfacewater. InMiddleCreek,mostMIWgroundwaterdischargingtosurfacewaterhassimilarcharacteristics tothe Formosa1 adit discharge, stronglyacidiccalciumsulfatewaterwith high concentrationsofiron,copper,zinc,andothertracemetals.InSouthForkMiddleCreek,MIWdischarging fromgroundwater tosurfacewaterisstronglyacidiccalciumsulfatewaterwith high concentrationsofcopper,zinc,andothertracemetalsandrelativelylowerironcontentascomparedto theUpperMiddleCreekarea. 1.3.2 Groundwater Datafromgroundwatersamplingshowthepresence of alluvial andbedrockgroundwatersystems, bothof which aretransporting inorganicstosurfacewater.The alluvialgroundwatersystemis presentwithindiscretealluvial aquifersthatarelocatedwithinunconsolidatedsedimentsin thebase oftributarydrainages.Thebedrockaquiferisafracturecontrolledaquiferhosted bymetavolcanicrocks. Findings of the limited groundwaterinvestigationsuggestthat leakagefromthewaterdiversionsystemattheFormosa1aditis rechargingthealluvialaquifer and contributing toMIWdischargesfromgroundwatertosurfacewaterintheupstreamreachesofUpperMiddleCreek.Althoughthereispotentialforthebedrockaquifertobeaffectedinthisarea, datafrombedrockmonitoringwellsMW8andMW2in thearea suggest theseeffectsareminor. Incontrast,thebedrockaquifer isaffectedwestofthe encapsulationmound in theheadwatersofSouthForkMiddleCreek.GroundwatersamplesfromMW5indicate groundwaterisacidicand

13


containshigh concentrationsof cadmium,copper,zinc,andotherinorganics.Thealluvialgroundwatersysteminthe headwaters areaof SouthForkMiddleCreekisaffectedbyMIW,withsimilarwater qualityto thebedrock groundwatersystem.

1.4 Ecological InvestigationsEcologicalstudieshaveincluded benthicmacroinvertebrate (BMI) sampling and fishsurveys/sampling.BMIsamplingwasconductedatover20locationsin1999 by BLMand OregonDepartment ofEnvironmentalQuality(ODEQ)(BLM/ODEQ2000).Dataobtainedduringthis samplingeventwerecomparedto earliersamplingthatwasconductedbytheU.S.FishandWildlifeService(USFWS)in1982and1984andthe OregonDepartmentofGeology andMineralIndustries(DOGAMI) yearlyfrom1994through1997(DOGAMI1990 to1999).Subsequent BMI communitysampling wasconductedbyBLMfrom2000to2008.SeveralfishsamplingeventswereconductedbyBLMandtheOregonDepartmentofFishandWildlife (ODFW)from1991 through 2007 (BLM2009). BMIandfishpresence/absencesurveys wereconductedfortheOU2BERAinMiddleCreekandSouthForkMiddleCreekinJune andSeptemberof2012andJune andSeptemberof2013.QuantitativeBMI communitysamplingfromaknown area(144square inches)wasconductedviaSurbersamplersinrifflehabitatatseverallocations.Fishsurveyswere conductedusingbackpackelectroshocking,focusing on poolsat thesamelocations. BMIsampling andfish surveysfollowedstandardizedprotocolsatallsamplingstationstoallowforcomparisonsof BMIrelativeabundanceanddiversityandfishpresenceorabsenceasdetailedinthe OU2 Data Gaps Assessment and Sampling and Analysis Plan Addendum (CDMSmith2012).BMIsamplesweresubmittedto theNationalAquaticMonitoringCenterLaboratoryatUtahStateUniversityforenumerationand identificationtolowestpossibletaxon. BMIandfishpresence/absencesurveys wereconductedatthreereferencestreamsinconjunctionwithsamplinginMiddleCreekandSouthForkMiddleCreekinJuneandSeptemberof2012 andJuneandSeptemberof2013. Figures 11a, 11b, and 11c showtheecologicalsampling locationsin additiontotheMXRand SFA2sampling locations.Adescription of thehabitat characteristics ofeach ofthesamplinglocationsis providedinSection2.2.1.1.

1.5 Organization of this ReportSection2servesastheProblem Formulationsection oftheOU2 BERA.Section3presentsthe ExposureAssessment,andSection 4presentstheEffectsAssessment.The informationpresentedin Sections3and 4areintegratedinRisk Characterization,Section5.Section6presentsthereferences fortheBERA.TablesandFigures areprovidedfollowing eachsection,andsupportingdocumentation isprovidedinappendices.

14

Table 11 Sampling Locations and Dates for Surface Water Samples

Location Type Oct 2009 Jan/Feb 2010

Oct 2010

Jan 2011

Sep 2011

Feb 2012

Jun 2012

Sep 2012

Jun 20131

Sep 2013

Apr 2014

MIDDLE CREEK Formosa 1 Adit ADIT x x x x x x x x x

A4 STREAM x x x A6 STREAM x

M1.2 STREAM M2.0 STREAM M3.0 STREAM x x x M3.1 STREAM x M5.5 STREAM x M7.9 STREAM x x x M9.8 STREAM M13.0 STREAM x x x MF1 SEEP x MF2 SEEP x x ME1 STREAM x ME2 SEEP x ME3 SEEP x x MXR STREAM x x x x x x x x x Seep A STREAM x x MA13 SEEP x MA17 SEEP x x x MA22 SEEP x MA40 SEEP x MA44 SEEP x dry MA46 STREAM x x x x x MA61 STREAM MB1 SEEP x x MB3 SEEP x

Martin Creek Reference STREAM

x

MREF1 STREAM dry x dry x Seep at A9 SEEP x

SOUTH FORK MIDDLE CREEK 404 Adit ADIT x x

404 Adit Lower ADIT SF0.7 STREAM o x SF1.0 STREAM x x x x x x x x x SF3.0 STREAM x x x SF4.7 STREAM x SFA1 STREAM x SFA2 STREAM x x x x x x SFA4 SEEP x SFA5 SEEP x SFA8 STREAM x SFB2 STREAM x x SFB4 SEEP x SFB14 STREAM x x x SFD1 SEEP x SFE1 SEEP x SFF1 SEEP x SFG1 SEEP SFG2 STREAM SFG3 STREAM x SFG4 STREAM SFREF1 STREAM x x x

Formosa Mine OU2 BERA 15

Table 11 Sampling Locations and Dates for Surface Water Samples

Location Type Oct 2009 Jan/Feb 2010

Oct 2010

Jan 2011

Sep 2011

Feb 2012

Jun 2012

Sep 2012

Jun 20131

Sep 2013

Apr 2014

RUSSEL CREEK SW3 STREAM x x SW4 STREAM x x SW5 STREAM x x

WEST FORK CANYON CREEK SW6 STREAM x x SW7 STREAM x x C1 STREAM x x x

COW CREEK CHAMBERS STREAM x x

SW1 STREAM x SW2 STREAM x

RIDDLE INTAKE FAUCET x x x x x x x Notes: Indicates YSI field parameters only collected at this location x Indicates YSI field parameters and laboratory sample collection at location BMI and fish o BMI 1YSI data not reliable for all parameters in June 2013


West F

orkCa

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Panther Creek

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r Mid

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reek

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Crk

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r But

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LegendEcological Sampling Locations # BMI only* G BMI, FishF " BMI, Fish, Surface Water) ! Surface Water(

Roads

Hydrology

Contours (100 ft)

Township/Range

Sections

0 0.125 0.25 0.5 Miles

Geographic Data Standards: Projected Coordinate System: NAD 1983 State Plane Oregon FIPS Zone 3602 Data Sources: Bureau of Land Management: 2001 Hydrography 2005 Township, Range, and Topography

Figure 1-1a Ecological Sampling Locations

05 T32S-R06W 04 03 02 Formosa Mine Douglas County, Oregon

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Hydrology

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Figure 1-1b03 T32S-R07W02 01 06 T32S-R06W

05 Ecological Sampling Locations

Formosa Mine Douglas County, Oregon

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Short Creek

Hutch Creek

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Calf Creek

Middle Creek

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LegendEcological Sampling Locations

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Section 2 BERA Problem Formulation TheProblemFormulationphaseof the OU2BERAestablishesthe goalsanddescribesthescopeand focusofthe assessment.Asdefinedin Section1,OU2 includes all surface water, sediment, groundwater, undergroundworkings, and adit water drainage associatedwiththeFormosaMine,whereasOU1 includesthesurfaceandsubsurfaceminewastesand soilsthatweredeposited outside ofthemineworkings.Thestudy area forthisBERAforOU2includestheaquaticecosystemspotentiallyaffectedbyMIW,specifically,Middle CreekandSouth Fork Middle Creek. Based on thefindingsof theOU1RI(CDM2012), surfacewaterqualityinbothMiddleCreekandSouthForkMiddleCreekisaffectedbyMIWas a resultofcontaminanttransportfromtheminewastes andsoilstothese surfacewaters viaprocessesof directaditdischargestoalluvium, infiltrationof rainfall, andgroundwater transport. Thisphaseof theBERA considers sitespecificregulatoryandpolicyissuesandrequirementsandidentifiespotentialstressors(e.g.,COPCs)andecologicalresourcespotentiallyat risk.Animportantoutcomeofproblemformulationistheconceptualsitemodel(CSM),whichdescribespotentialexposurescenarios,includingcontaminantsources,transportmechanisms,exposuremedia,exposureroutes,andreceptors.InformationdepictedintheCSMisused torevealrelationshipsbetweenminerelatedchemicalstressors, ecologicalreceptors,assessmentendpoints,measurementendpoints,andpreliminaryremedialactionobjectives.Eachofthese componentsisdefinedanddescribedinthe following sections.ThesitespecificCSM isdiscussedinSection2.4andpresentedin Figure 21.

2.1 Stressor Identification Ecologicalstressorsaredefined as physical,chemical,orbiological entitiesorconditions that adverselyaffectorhavepotential toaffectadverselyecologicalreceptorsdirectly orindirectly.This BERAis focusedonthepotential ecologicaleffectsassociated withinorganiccompoundsinsurfacewater,based onthefindingsof theSLERAfortheOU1RI,which identifiedminerelatedstressorsas inorganicchemicals (cadmium, copper,andzinc) and possiblyotherminingrelatedstressors suchaspH. Otherstressors,including physical(nonchemical)stressorssuchashabitatdisturbanceordegradation, may contribute to adverseecologicaleffectswithintheaquaticecosystemsofinterestintheOU2BERA.Habitatdegradationisobservedwheresurfaceand subsurfaceminewastesandsoilsweredepositedoutsideofthemine workingsandwithinseepsclosetothemine.One exampleofthis degradation that is easily observedisthepresenceofmetalprecipitatesthatcancoversubstrateandnegativelyaffectBMIandother aquaticorganisms.Asdescribed inSection2.2.1.1,metalprecipitates havebeenobservedasorange staining andwhiteturbidwaterin upstreamreachesofMiddleCreekandSouthForkMiddle Creek,respectively.Thus,habitatdegradationis evidentinthe aquaticecosystemsofconcernintheOU2BERA.However,thisoccursatonlythemostupstreamecologicalsamplinglocations. TheeffectofMIWonsurfacewateristhefocusofthe OU2BERA.As describedinSection2.2.1.2,verylittlefinegrainedsedimentwas foundduringecologicalinvestigationsfortheOU2BERA, indicating thatexposuretominerelatedCOPCsinsedimentisnotexpected tobea significantexposurepathway

21

Section 2 BERA Problem Formulation

forBMIor fishthat consumeBMI. Therefore,theabioticmedia of concernforaquatichabitatsis limitedtosurfacewater. 2.1.1 Chemicals and Exposure Media of Potential ConcernTheOU1SLERApreliminarilyidentifiedtheCOPCs,sourceareas, ecologicalhabitats,andecologicalreceptorsofpotentialconcernconsideredapplicabletotheOU2 BERAfortheaquaticecosystems. COPCsidentifiedintheSLERAincludecadmium, copper,andzinc.TheseCOPCs were identifiedbasedonascreeningofdissolvedconcentrationsofselectedmetals(cadmium,copper,lead,nickel, andzinc) insurfacewaterintheupperreachesofMiddleCreekandSouth ForkMiddleCreek. Terrestrialandriparianhabitats uplandofandadjacenttoMiddleCreekandSouth ForkMiddleCreekarenotexpectedtobeaffectedadversely byminerelatedmaterials.AsdescribedintheOU1RI,thesignificantfateandtransportmechanismforCOPCs fromOU1is transportviagroundwater,which dischargesto surfacewatersin theupperreaches ofthecreeks.Terrestrialhabitatsthatwereimpacteddirectlybyminematerials or have the potentialtobe impactedbyCOPCs via surfacerunofffromminematerialswere evaluatedas partofOU1andarenotincludedintheOU2BERA. AdditionalabioticandbiologicalsamplingandsurveyswereconductedinsupportoftheOU2BERA tosupplementthispreliminaryinformationandfurther identifyCOPCsandexposuremedia.Thefindings of ongoing surface waterandgroundwatersamplingand ecologicalinvestigationsconductedin2012,2013,and2014wereevaluatedinthe OU2BERA torefinethelistofCOPCs.SurfacewateristheexposuremediumofinterestintheOU2BERA. 2.1.2 Refinement of Chemicals of Potential Concern Whilethe OU1SLERAevaluatedonlyfivemetals(cadmium,copper,lead,nickel, andzinc), thescreeningevaluationconductedfor theOU2BERAincludedastandard targetanalyte listof 26metals (aluminum, antimony, arsenic,barium,beryllium,cadmium,calcium,chloride,chromium,cobalt,copper,fluoride,iron,lead,magnesium,manganese, mercury,nickel,potassium,selenium, silver,sodium, sulfate,thallium,vanadium,and zinc).TheCOPC screeningprocessforthisBERA includedcomparisonsofmaximumdetected concentrationsofthesemetals insurfacewatertoconservativeESLsapplicabletodiverseaquaticlifecommunities(i.e.,BMI, fish, aquaticplants,andlarvalamphibians). Chemicalsassociated with maximum detectedconcentrationsexceedingESLswereretainedasCOPCsfortheOU2BERA.Thisscreeninglevelmethod isdescribedfurtherinSection3.5.Basedonthisscreening,cadmium,copper,mercury,andzincwereretainedas COPCsforfurtherevaluationintheOU2BERA. 2.1.3 Summary of Exposure AreasSurfacewatersofconcerninthe OU2BERAincludeMiddleCreek andSouthForkMiddleCreek.Eachofthesestreamsis identifiedasseparate exposureareas(EAs), and each is applicable to mobileaquaticreceptorssuchasfish thatmovethroughoutthesecreeks. TheMiddleCreekEAisshownin Figures 11a, 11b,and 11c.TheSouthForkMiddle Creek EA is shown in Figure 11a. Chemical exposuredata applicabletofish andothermobileaquaticreceptorsarebasedondatafortheentire EA(e.g.,mean dissolvedcopper concentrationsforMiddleCreek).Chemicalexposuredata fornonmobileorminimallymobilereceptors,suchasBMI,donotutilizeEAsasdescribedabovebutinsteadare based ondata from unique surface water and biological samplingstationslocatedoneachof thesecreeks,asdescribedbelow.

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2.2 Ecological Resources at RiskThefollowing sectionssummarizeinformationfrom availabledocumentsofpreviousstudies intheMiddleCreekwatershedandfromecologicalandhabitatobservationscollectedduring sampling and reconnaissancesurveysconductedin2012and2013. 2.2.1 Habitats AsdescribedinSection1.4,OU2 ecologicalinvestigationswere conductedinMiddleCreekandSouth ForkMiddleCreekinJune andSeptemberof2012andJune andSeptemberof2013. 2.2.1.1 Aquatic HabitatsMiddleCreekandSouthForkMiddleCreekoriginateasseepsneartheformermining area.Multiple seepsandtributariescontribute toeachsurfacewatersystem. Flumeswithcontinuousautomatedflowmonitoringandwaterchemistryinstrumentationwereinstalledin or near theheadwatersof bothsystems.Aflume was installedat MXRforMiddle Creekand atSFA2forSouthForkMiddleCreekto collect data on flow and water quality and better define seasonalfluctuations indischargeofcontaminated waters. AquatichabitatsofinteresttotheOU2BERAincludehighergradient/highenergyreachesofMiddleCreekandSouthForkMiddleCreek aswellaslower energyreachesdowngradientoftheformerminingarea.Thesehabitatsincludeperennialinstreamsections ofthesewaterbodiesaswellasmargins and other areas that may beonlyintermittentlywet.HabitatobservationsaswellasobservationsoftheBMIcommunitiesandfish during ecological samplingin2012and2013are describedbelow. Figures 11a, 11b, and 11c showtheecologicalsamplinglocationsinadditionto the MXR andSFA2 sampling locations. Middle Creek Sampling LocationsMiddleCreekextendsapproximately13milestoitsconfluencewithCowCreek. CowCreekisatributarytotheSouthUmpquaRiverthatultimatelybecomesthe UmpquaRiver,whichreachestheoceanatWinchesterBay. TheheadwatersofMiddleCreekconsist ofseveralsmallseepsthatflowdownsteepslopesthroughmature coniferousforest dominatedby Douglas fir (Pseudotsuga menziesii).Thesedrainages convergeupstream ofthe MXR sampling locationwheretheflumeislocatedandcontinuousflowand waterqualitymonitoringisconducted.MXR islocatedapproximately0.7milesfrom theFormosaMineandisasecondorderstream. Thesubstrateat MXRconsistsoflarge cobble,andpartial armoring (coating and/or cementingoftherocksbymetalprecipitates)of thesubstratehas beenobserved.Disturbanceof thesubstrate duringsomeperiodsoftheyearresultsinmilky,turbidwater.Finegrainsedimentisgenerallylacking.Whilenoecological sampling has beenconductedatMXR,the BMIcommunity islikely impaireddue tomine drainage and armoring ofthesubstrate.Theculvertjustdownstreampresents a barriertofishaccesstoMXRunder mostif notallflowconditions. TheM1.2 samplinglocationis approximately0.5milesdownstreamofMXR and1.2 milesfromthe mine,asmeasuredfrom thesurfacewaterdrainage headwaters nearestthemine.This isathirdorderstream witha gradient of about 3%.The substrate consists primarilyof large cobblesandsmall boulders,withsomearmoringand orangestaining.Thebankfull widthofMiddleCreekatthislocationisabout12feet,andthebanks arehighlyincisedinareasalongthisreach.Averagedepthofthestreamisabout0.5feet.Ripariancover isgood,consistingof redalder(Alnus rubra),vinemaple(Acer circinatum), andDouglas firwith95%canopycoverage overthestream.Largewoodydebrisanda

23


fewpoolswith depthsof1 to2 feetarepresent.Finegrained sedimentis limitedtosmall amountswithinpoolareas.Duringecologicalsamplingin2012and2013, veryfewBMIwereobservedatM1.2.Onecutthroattrout(Oncorhynchus clarkia)wasobservedatM1.2inbothSeptember2012andJune2013,andtwocutthroattroutwere observedinSeptember2013. TheM2.0 samplinglocationis approximately0.8milesdownstreamofM1.2and2milesfromthemine.Thisisafourthorderstreamwitha gradientofabout1.5%.Thesubstrateconsistsprimarilyof cobble.Bankfull width isaround17feet,withanaveragedepth of0.5feet.Asmallnumberof 1to2footdeeppoolsarepresent.Finegrainedsedimentis generally lacking butmay bepresentwithin pools.Analgalmuckwasobservedduringall2012and2013 sampling events.Attheroad crossing, thereisanapproximately12foot gapintheriparianvegetation,butelsewhere thereisagoodripariancorridorconsistingof redalder,vinemaple,andDouglasfir,providinganaverageof 60%overstream shade.Duringsamplingin2012and 2013,veryfewBMIwereobserved.Youngofyearsalmonids(notidentifiedtospecies)wereobservedinboth2012 and2013.Roughskinnednewt(Taricha granulosa) andlarval Pacific giant salamanders (Dicamptodon tenebrosus)werenoted. TheM3.0 sampling locationis approximately1mile downstreamofM2.0 and3 milesfromthemine.Thisisafourthorderstreamwithagradientaround2.5%.The averagebankfullwidthis16feet,andaveragedepthis 0.5feet.Thesubstrateconsistsprimarilyof cobblewitha fair amountof bedrock present.Finegrainedsedimentislimitedbutmaybepresentwithinshallowpools. Thereisverygoodripariancover consistingofred alder,vinemaple,and Douglas fir, providingan averageof95%overstream shade.TheBMIcommunityappearedgoodduring sampling in2012and2013.Duringfishsurveysin2012and2013,youngofyearsalmonidswereobserved.Roughskinnednewtand Pacificgiantsalamanderswerenoted. TheM3.1 samplinglocationis approximately0.1milesdownstreamofM3.0and3.1 milesfromthemine.ItisjustdownstreamoftheconfluenceofMiddleCreekandSouthForkMiddleCreek.Thisisafifthorderstreamwith a gradientofabout2%. Thesubstrateconsistsofcobbleandgravelwithsomebedrock.Orangestainingandmuckymaterial was notedonthesubstrateinsomeareas.Finegrainedsedimentisgenerallylacking but maybepresentwithinpools. Thebankfullwidthisaround 20feet,with anaverage depthofabout1 foot.Thedominantriparianvegetationconsistsofredalder,willow (Salix sp.),andDouglasfir,andthereare instreamislandscovered withgrasses.Overstreamshadeisabout50%. GoodBMI community was observedduring sampling in2012 and2013.Youngof yearcutthroattrout,cohosalmon(Oncorhynchus kisutch), steelhead/rainbow trout(Oncorhynchus mykiss),and sculpin (Cottus sp.)wereobservedin2012and2013.Inaddition,asteelhead reddwas observedatM3.1inJune2013. TheM5.5 samplinglocationis approximately2.4milesdownstreamofM3.1and5.5 milesfromthe mine.Ecologicalsamplingwasonly conductedatthislocation inJuneof2012.Thisis afifthorderstream witha gradient around 1.5%.Riparianvegetationisdense,consisting ofalder,willow,andvinemaplewithinstreamislandscoveredwithgrassesandotheraquaticvegetation.The bankfull width isapproximately23feet, and average depth is about 1 foot, with 2footpools.Overstream shadecovers around50%ofthestream.Thesubstrate ispredominantlycobbles with a few bouldersandsome bedrockpresent.Finegrainedsedimentisgenerallylacking but may bepresentwithin pools. TheBMI communityappearedverygoodduringsamplinginJune2012. Young oftheyearcohosalmon, rainbowtrout,sculpin,androughskinnednewtwereobserved. TheM7.9 samplinglocationis approximately2.4milesdownstreamofM5.5and7.9 milesfromthe mine.This isasixthorderstream witha gradient of approximately 1.5%.Thesubstrateconsistsof

24


cobblesandsomegravel.Bankfull width isapproximately32feet,andaverage depthisabout 1foot, with pools upto3feetdeep.Sedimentislimitedbut maybepresentwithinpools.Riparianvegetationisdenseandconsistsofalderandwillow, with instreamislandscoveredwithgrassesandother aquaticvegetation.Canopycovershades around 50%ofthestream.TheBMIcommunityhereappearedverygoodduringsamplinginboth2012and2013. Young oftheyear coho salmon,cutthroat trout,andsculpinwereobservedduringsurveys.Beaver(Castor canadensis) signandroughskinned newtwereobserved. TheM9.8 samplinglocationis approximately1.9milesdownstreamofM7.9and9.8 milesfromthe mine.Ecologicalsamplingwasconductedonly atthislocationinJuneof2012.Thisis asixthorderstream witha gradient around 2%.Bankfullwidth isapproximately29feet,andaveragedepthisabout8inches,withpools upto2.5feetdeep.Thedominantsubstrateisgravel.Sediment islimitedbutmaybepresentwithinpools.Riparianvegetationisdenseandconsistsofalder andwillow, withinstreamislandscoveredwithgrassesandotheraquaticvegetation.Canopycovershadesaround60%ofthestream.TheBMIcommunity appearedverygoodduring samplinginJune2012.Youngofthe yearcohosalmonwereobserved alongwithcutthroattroutandsculpin. Beaversignandroughskinnednewtwereobserved. TheM13 samplinglocationisapproximately3.2miles downstream ofM9.8 and13milesfromthe mine.Ecologicalsamplingwasonly conductedatthislocation inJune2012.M13 isjustupstreamoftheconfluenceofMiddleCreekandCowCreek.Atthislocation, MiddleCreekisverywidewithan approximate bankfull width of 44 feet.Atthislocation,thestreamconsistsmostlyofshallowriffle habitatofaround10 inchesdeepwithsomepools upto3.5 feet deep.Thisisasixthorderstreamwith a gradientaround1.5%. Sedimentisgenerallylacking butmay bepresentwithinpools. Theriparian corridorisdominatedby matureOregonmyrtle(Umbellularia californica)andOregonash(Fraxinus latifolia)andshadesapproximately80% ofthestream.The dominantsubstrateisgravelwithsome cobble.TheBMIcommunity appearedverygoodduring sampling in June2012. Youngof theyearcoho salmonwereobservedalongwithrainbowtrout,sculpin,anddace(Rhinichthyssp.).Aroughskinned newtwasobserved. South Fork Middle Creek Sampling LocationsSouthForkMiddleCreekbeginsin aseriesofsmallseeps,includingSFA2,wherea flume hasbeeninstalledtomeasureflowandwaterqualityparameters.SouthForkMiddleCreekflowsapproximately 5milestoitsconfluencewith MiddleCreek.In June2012,severallocationsalong SouthForkMiddleCreekwerevisitedduringtheOU2BERAsitereconnaissance.Locationswereselectedtobeconsistentwith previoussampling by BLMand others.Thefurthestupstream locationvisitedonSouthFork MiddleCreekwasSF0.7,located approximately0.7milesfromtheFormosaMineand0.3milesupstreamofSF1.0,alocationwherewaterqualitysamplingisconductedtwiceperyear. TheSF0.7 locationisa third orderstreamwitha gradientaround 3%.Thesubstrateconsistsofboulders,cobble,andgravel.Finegrainedsedimentwaslargely absentduringthesitevisitinJune 2012.Riparianvegetationisdense andconsistsofDouglasfir, bigleaf maple(Acer macrophyllum),andvinemapleshading approximately95%ofthestreamandan understoryofsalal(Gaultheria shallon)andOregongrape (Mahonia aquifolium). Bankfull widthis6 feet,andaverage depth4inches.During theJune2012visit,highlyturbid, milky waterwasobserved whenthesubstratewas disturbed,indicating the presenceofmetal precipitates.BMIsamplingwas conducted,butno fishsurveyswereconductedbecauseofthelowwaterlevelandgenerallack ofsuitable habitat for fish. Ecological samplingsubsequentlywasnotrepeatedatthislocation.

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TheSF1.0 sampling locationis approximately1mile fromtheFormosaMine.Atthis location,thereisalargepool(aroundthreefeetdeep)downstreamofalarge culvertunderaroadcrossing.TheSouthForkReferencestream(describedbelow)entersSouthForkMiddleCreekjustdownstreamofSF1.0.TheSF1.0 locationisa fourthorderstream,and thestreamgradient at thislocation is approximately1.5%.Thedominantsubstrateis cobble.Theripariancorridorisdenseandconsistsofredalder,bigleafmaple,vinemaple,andDouglasfir,shadingapproximately80%ofthestream.Thebankfullwidth is approximately 19feet, and average depth is approximately8inches.Asmallamountoffinegrainedsedimentispresentwithin pools.Duringsampling in 2012and2013, theBMIcommunity wassparse.Small numbers(1 or 2)ofcutthroat andrainbowtrout havebeenobservedduringfish surveys. TheSF3.0 samplinglocationis 2 milesdownstreamofSF1.0and 3milesfrom themine. Thereisa largeculvert onthedownstreamendthatlikelypreventsfishpassage exceptduring highflows.Thisis afifthorderstreamwithagradientofapproximately1.5%. The dominantsubstrateiscobble,withsomesandpresent.Finegrained sedimentisgenerallylackingbut may bepresentin small amounts withinpools.Thebankfullwidth isapproximately30 feet,with anaveragedepthof 0.5feet.Riparianvegetationconsistsofred alder,bigleaf maple,vine maple,andDouglasfir,withcanopycoverage around75%. During sampling, theBMI communityappearedfair.Highernumbersoffish,including cutthroat andrainbow trout,havebeenobservedduring fishsurveysascomparedtoSF1.0.Roughskinnednewtshavebeenobserved. TheSF4.7 samplinglocationis approximately1.7milesdownstreamofSF3.0and4.7 milesfromthe mine.Ecologicalsamplingwasonly conductedatthislocation inJuneof2012.ThislocationisjustupstreamoftheconfluencewithMiddleCreek.Downstreamofthe confluence,MiddleCreekrunsbyalargegroupcampsite. This isafifthorderstreamwithagradientofapproximately4%.Dominantsubstrateisbouldersandbedrock,andthereislittle sediment present.Bankfullwidthis approximately19feet, withanaverage depth of8inches.Riparianvegetationconsistsofredalder, vinemaple, willow,and Douglasfir,shading about60%ofthestream.DuringsamplinginJune2012,theBMIcommunityappearedgood. Young oftheyearcohosalmon andlarger rainbowtroutwereobserved, along with Pacific giant salamanders. Reference Sampling LocationsTheMiddleCreekReferencelocation(MREF) isonasmalltributarystreamapproximately0.3milesfromitsconfluencewithMiddle Creek,whichisapproximately0.1 milesdownstreamofM1.2.Atthislocation,thereisa large culvertlocatedunderaroadcrossing. Thisisa thirdorderstream withagradientofapproximately1.5%. Dominantsubstrateiscobble,andthereislimitedsedimentpresent.Theriparianvegetationconsists ofredalder,vinemaple,and Douglasfir,shading about90% ofthestream.Bankfullwidthisapproximately6feet,andaveragedepthisabout4inches.Downstreamoftheculvertisapool,about 1.5 feetdeep. Duringsampling,theBMI communityappearedgood.In Juneof2012,nofishwereobserved,butroughskinnednewtsandaPacific giant salamander were found.InSeptemberofboth2012 and2013, thestreamwasnotflowing, sono sampling wasconducted.In June2013,nofishwereobserved,butsimilar toJune2012,two roughskinnednewtswerefound along with several young Pacificgiantsalamanders. TheMartinCreekReferencelocationis approximately0.3miles upstream along MartinCreekfrom itsconfluencewithMiddleCreek,whichisapproximately0.5miles upstreamofM7.9.This isafifthorderstream witha gradient of around 2%.The dominantsubstrate is cobble,andthereislittlesedimentpresent.Bankfullwidthisaround19feet,andaveragedepthis about6 inches.Theriparian vegetation

26


consistsofaldersandwillows, providingabout90%overstream shade.During sampling, theBMI communityappearedverygood.Young oftheyearcohosalmonand troutfrywereobservedalong with sculpin andoldercutthroat troutandsteelhead.Pacificgiantsalamanders wereobserved atthislocation. TheSouthForkMiddleCreekReference location(SFREF)isapproximately0.7milesupstreamofSF1.0onatributarystreamtoSouthForkMiddle Creek.Thisis afourthorderstreamwithagradientofapproximately1.5%.Thereisaroadculvertwithalargepool(about3.25feetdeep)onthedownstreamend.Thedominantsubstrateiscobble.Thereissome sedimentpresent.Thebankfull widthisabout6feet,with an averagedepthofabout 0.5feet outsideofpools.Riparianvegetationconsistsofredalder,vine maple,andDouglas fir,providing about90%canopycoverage.During sampling,the BMI communityappeared verygood.Cutthroattrout (noyoungoftheyear)wereobservedduringfishsurveys. 2.2.1.2 Fate and Transport within Aquatic HabitatsSurfacewaterqualityinboth MiddleCreekandSouthForkMiddleCreekisaffectedbyMIW,primarilyfromdischargeatseepsreceiving contaminants from groundwater.Basedonthe findingsof theOU1 RI(CDM 2012),theprimarymeansoftransportofMIWisvia alluvialgroundwaterasaresultofleaching and directdischargefromtheFormosa 1Aditandsubsequentdischargetosurface waters.DirectrunoffofMIWfromthemine materialswouldonlybe expectedtooccurafter intensebutshorttermprecipitationorsnowmeltevents,which occur primarilyduringlatefallthoughwinter. Basedonobservationsduringecologicalsamplingin2012and2013,finegrainedsedimentsareminimal withinbothof thesesurfacewaterdrainages,particularlyinhighergradientupperreachesandthosedominatedbycobbleandbouldersubstrates.Smallamountsofsedimentarepresentwithinlargerpools, typicallylocateddownstreamofculverts.Thisindicatesthatsedimenttransportdownstreamisnot likelya significant means of transport of minerelatedmetals fromOU1tothe downstreamaquaticsystemsof concernintheOU2BERA. Inaddition,ecological data onBMIcommunitiesatseveralsamplinglocationsdescribedaboveare representativeofrifflehabitats thatare generallylacking in finegrainedsediment.Sincebenthicmacroinvertebratesinhabittheseareasthatappeartobegenerallylackingfinegrainedsediment,exposuretominerelatedCOPCsin sedimentisnotexpectedtobe a significantexposure pathway forbenthicmacroinvertebratesorfishthatconsumeBMI.Therefore, theabiotic media ofconcernforaquatichabitatsislimitedtosurfacewater. 2.2.1.3 Terrestrial Habitats UplandUplandvegetationwithin theOU2 BERAstudyareaconsistsprimarilyofconiferousforestdominated byDouglas fir.Goldenchinkapin(Castanopsis chrysophylla)andPacificmadrone(Arbutus menziesii)commonlyoccurindrierareaswhilewesternredcedar(Thuja plicata)andwesternhemlock(Tsuga heterophylla)occurinwetterareasoronnorthaspects.Forestageinand aroundtheminevariesfromoldgrowthstandstoyoungersuccessionalforestandareasofrecenttimberharvest.Openingsinthecanopyallow forgrowthof herbaceousvegetation,shrubs,andsaplings.Opendryareasaredominatedby wedgeleaf ceanothus(Ceanothus cuneatus)andothershrubsas wellasDouglasfir saplings.Grassesandpoisonoak(Toxicodendron diversilobum)becomemoreabundantonopen,sunny,southaspectswithinthestudyarea.Wildlife andplants foundinthestudyarea arelistedin Table 21.

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RiparianRiparianvegetationinandaroundthe OU2BERAstudyarea isdominatedbydeciduoustreesand shrubs,includingvine maple,bigleafmaple,andredalder.AlongdownstreamreachesofMiddleCreek,blackcottonwood(Populus trichocarpa),willow,Oregonash,andOregonmyrtleoccur.Sword fern(Polystichum munitum)andthimbleberry(Rubus parviflorus)arecommonunderstoryriparianspecies.Douglas firoccurs adjacenttostreamsinand aroundthestudyarea.Wildlifeandplantsfound inthe OU2BERAstudyarea arelistedin attached Table 21. Terrestrialandriparianhabitatsadjacenttostreams werecharacterizedusingfieldobservationsand incorporatingtheuseoftheEcologicalRiskChecklist adapted fromEPAguidanceforuseonhazardouswastesites.Examplesofcharacteristicsthatwerenotedviaobservationincludedominantplantspeciesinthe overstory, understory,andgroundcoverwithin theBERAstudyarea withspecificemphasisonhabitatsadjacentto thestreams.Theseobservationsareimportantfordocumentingtheterrestrialhabitatsusedbybreedingandnestinganimals,including listedspecies,within the OU2BERAstudyarea. 2.2.1.4 Fate and Transport within Terrestrial HabitatsBasedonobservationsduringecological sampling, the primarymeansoftransport ofminematerials totheaquaticecosystemsisvia discharge ofMIW. MIW istransportedingroundwatertoseepsthatfeedMiddleCreekandSouthForkMiddleCreekandinsurfaceflowsthroughprecipitationonexposedminewastesandmineimpactedsurfacesoils.Theterrestrialhabitatsaffected byminematerialswereevaluatedintheOU1RI(CDM2012).ThescopeoftheOU2BERA andmedia evaluatedaredescribed inSection2.1.1.TheOU2BERAfocusesonassessingriskwithin aquatichabitats.Riskstoterrestrial habitatsandreceptorsarenotevaluatedquantitativelyin the OU2BERA. 2.2.2 Ecological ReceptorsFollowing theSLERA from OU1,the scopeoftheOU2BERAandmediaevaluated isfocusedonassessingriskwithinaquatichabitats. 2.2.2.1 Aquatic ReceptorsAquaticreceptorsofinteresttotheOU2BERAincludeaquaticplants,watercolumn andBMI,fish,and larvalamphibians.Severalamphibianspecies,includingroughskinnednewtand Pacificgiant salamander, areknowntooccurin MiddleCreekand SouthForkMiddleCreekandwereobserved during ecologicalsampling, as describedabove. Freshwaterfishthatareknownto occur inthe aquaticecosystemswithintheOU2BERAstudyarea includecohoorsilversalmonand steelhead/rainbowtrout.Fish speciesobservedduring fish presence/absencesurveys conductedin2012and2013includecohosalmon,steelhead/rainbow trout,cutthroattrout,andsculpin. BothPacificlamprey(Entosphenus tridentatus)andwesternbrooklamprey(Lampetra richardsoni)havebeendocumenteddownstreamof thestudyarea at theODFWsmolttrapinCowCreek(BLM 2002).Threelampreys(speciesnot identified)wereobservedin MiddleCreekduringpresence/absencesurveys in1984and1988(Norecol1989).In1993,threelampreys(3to4incheslong)wereobservedinMiddleCreekaboveBrushCreekduringsurveysconductedbyODFW(BLM2002).

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Lampreyswerenotobservedinthe studyareaduringfish surveyscompletedbyBLMfrom2000to 2007orby EPAin2012and2013. The nonobservancemaybeattributedtoelectroshockingsamplingtechniquesused,whicharenot thepreferredmethodforcollecting oridentifying thepresenceoflampreys.Inaddition,localized habitatlimitationsorphysicalbarrierstofishpassagemay have precludedfindinglampreysatthetime ofthesesurveys. Importantmetricsrelated tofish asreceptorsincludefielddata suchas numberof fishobservedbyreach, number of fish taxa for a given reach, and ancillary information,includingnumberof coho salmonand/orsteelheadreddsper specificstreamreach.Other importantdata relatedtofishas receptorsincludewaterqualitysuch aspH,turbidity, anddissolvedmetalsconcentrationsinsurface water.Metrics suchastheseare usedtocharacterizecurrentconditionswithrespect tosuitabilitytosupportfishsurvival,growth,andreproduction.Asubstantial amountof fish surveyworkhas beenperformedinthestudyareawaters overthepastseveral decades.TheOU2BERAreliesonthe resultsoftheseefforts,supplementedby recentlycollecteddata,tocharacterizethebaselineconditionsofthe aquaticenvironmentsofinterest. Similarly,benthicinvertebrates serve asimportantaquaticreceptors,as waterqualityaffectsBMI,andthereforethesereceptors canbe usedtoassessphysicalhabitatsuitability,surfacewaterquality,andsedimentquality.Asdiscussedabove,thegeneral lackoffinegrainedsedimentpresentinthe aquatic ecosystemswithinthestudyarea indicatesthatsurfacewaterqualityistheprimaryexposuremedium forfocusoftheOU2BERA. ManyBMI specieshatchfromeggs laid byadultsin thesummerandgrowduring thefall, winter,and spring months,emerging asadultsinlatespring orsummer.Thus,theyareexposed to water quality conditionsinthestream throughouttheyear. Inhigherenergyreachesofthestreams(i.e.,riffles),itis expectedthatdominant BMItypeswouldincludeEPTtaxa(Ephemeroptera [mayflies],Plecoptera[stoneflies],Trichoptera[caddisflies]).EPTtaxaaregenerallyconsideredsensitivetodissolvedmetals(Maretetal.2003, Gerhardtetal.2004).Inslower,lowerenergyreachesofthesestreams,itisexpectedthatEPTtaxawillstillbedominantbutofdifferentspecies,withlikelysmallernumbersofnonEPTtaxa (e.g.,dipterans or fliesandpossiblyworms and snails) comprising the BMI community. Asforfish, BMImetricsrelatedtoabundanceand diversityareimportantmetrics for characterizing aquatic habitatsassuitableorimpaired.BecauseBMI(1)aregenerallynonmobileorhavelimitedmobility;(2) havelifecyclesthat generallyspan1to2years;(3)integratephysical,chemical,andbiologicalvariability overa long timeperiod;and(4)are intimatelyexposedtobothsurfacewaterandsediment,theyare excellentindicatorsofwaterand sedimentquality.Asdescribed inSection2.2.1.2,sedimentexposuresare notconsideredsignificantbasedonthe general lack offinegrainedsedimentinprimaryBMI habitat.Much BMI surveywork has beenperformedinthe studyarea waters overthepast severaldecades,andtheOU2BERAreliesontheresultsoftheseefforts, supplementedbyrecentlycollecteddata,tocharacterizethebaselineconditionsoftheaquatic environmentsofinterest. 2.2.2.2 Terrestrial ReceptorsTerrestrialreceptorsofinterest totheOU2BERAincludewildlifethatuseshabitatsdirectlyadjacenttothestreamsandnearbyforest habitats.Common wildlifewithin theBERAstudyarea includeseveralspeciesofmammals such as Rooseveltelk(Cervus canadensis roosevelti),blacktaileddeer(Odocoileus hemionus columbianus),coyote(Canis latrans),westerngraysquirrel(Sciurus griseus),andblackbear(Ursus americanus). Commonbirdspeciesfound in the BERA study area include common raven(Corvus corax),Stellersjay(Cyanocitta stelleri),mountainquail(Oreortyx pictus),redbreasted

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nuthatch(Sitta canadensis),blackcappedchickadee(Poecile atricapillus),bushtit(Psaltriparus minimus),and rufous hummingbird(Selasphorus rufus). Asdescribedabove,theprimary meansoftransport ofcontaminantstotheOU2BERA studyarea isviasurfacewaterandgroundwater,andnotsurfacesoils. Therefore,theexposurepathwayofinterestforterrestrial receptorsrelates touseofaquatichabitats(e.g.,drinking surfacewater,consuming aquaticbiota).Terrestrialanimals,includingbandtailedpigeon(Patagioenas fasciata)anddeerhavebeenobserved drinkingfromtheFormosaadit.However,because theseterrestrialanimalsaremobile and have large foraging ranges, theirexposuretocontaminants viadrinkingwaterinMiddle CreekorSouthForkMiddleCreekis consideredinsignificant. 2.2.2.3 Federally Listed Species Federal Endangered and Threatened SpeciesThereare11federallythreatened orendangeredspeciesunderthe jurisdiction oftheUSFWS thathavepotentialtooccur inDouglasCounty(USFWS2013).Ofthese,sevenare marinespeciesorassociatedwithcoastalhabitatsnotfoundclosetotheOU2BERAstudyarea.Theremaining fourspeciesincludetheNorthernspottedowl(Strix occidentalis caurina)andthreeplants:Gentner's fritillary(Fritillaria gentneri),Kincaid'slupine (Lupinus sulphureus ssp. kincaidii),andrough popcornflower(Plagiobothrys hirtus).Inaddition,threespecies,thefisher(Martes pennanti),theNorthOregon Coastdistinctpopulationsegmentofredtreevole (Arborimus longicaudus), andwhitebarkpine(Pinus albicaulis)arecandidatesforlisting.A listofthefederallythreatened andendangeredspeciesisprovidedin Table 22 alongwiththepotentialfor eachspeciestooccurwithin theBERAstudyarea.Specieswith highpotentialtooccurareshadedinthe table. TheNationalMarine FisheriesService(NMFS)liststhreespecies with potential tooccur in ornear theBERAstudyarea,including Oregon Coast cohosalmon,greensturgeon (Acipenser medirostris),andeulachon(Thaleichthys pacificus)(NMFS2013). Federal Species of ConcernThereareanumberoffederalspecies ofconcernwithpotential tooccur in ornear theOU2BERAstudyarea basedontheUSFWSlistforDouglas County(USFWS2013)andNMFSregionallists(NMFS2013).Speciesofconcernhavea conservationstatusthatisof concerntotheUSFWSandNMFSbut forwhichfurtherinformationis stillneeded.Thesespeciesinclude13birds,9 mammals,7 fish,10reptilesandamphibians,5 invertebrates, and17plants.Federalspeciesofconcernarelistedin Table 22 alongwiththepotentialforeachspeciestooccurwithinthe OU2BERAstudyarea.Specieswithhighpotential tooccur areshadedinthe table. Food Web Model ReceptorsAsdiscussedfurtherinSection 3.6.2,findingsfromtheinvestigations and nature of water qualitydeterminedthatfoodwebmodelingwasnotnecessaryandwasnot performed fortheOU2BERA.The COPCsidentifiedfortheOU2BERA includecadmium, copper,mercury,andzinc,whichareallbioaccumulativeorpotentiallybioaccumulativechemicals.Cadmium appearstoaccumulate in lower trophiclevelsbut notin upper trophiclevelsvia dietaryexposures. Copperandzincareessentialelementsforlife,andsomeaccumulationisexpected.Onlyatveryhighdosesarecopperandzinctoxictouppertrophiclevelreceptorsvia diet,yetsuchdosesareunlikelyheregiventheconcentrations measuredinsurfacewaters andtheexpectationofinfrequentandshortdurationforagingonsitebyuppertrophiclevelreceptors.

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Anevaluationofseverallinesof evidencesupportstheassumptionthatmercuryis notminerelatedanddoesnotposeaconcernfor ecologicalreceptorsintheaquaticecosystemsofinterestfortheOU2BERA.TheselinesofevidencearedescribedindetailinSection3.6.2.1.Thelinesofevidenceevaluated include: Resultsoflowlevelanalysisof mercuryinupstreamsurfacewaterlocationsclosetothe FormosaMine

Lowfrequencyofdetection(10%)and low concentrationsinsurfacewatersamples Comparisontomercuryconcentrationsinotherdrainagesconsideredbackgroundorreference Informationonhistoricaloperations Limitedfish tissuesamplingbyODEQ(2004)

Basedontheselinesof evidence,foodwebmodelingassociated withexposuretomercuryisnotwarrantedfor aquaticreceptors.

2.3 Endpoints and Risk Questions/HypothesesTheOU2BERAisfocusedonassessingpopulationlevelrisksassociatedwithminerelatedcontaminationin abiotic media.Ingeneral,risksareassessed bycomparingCOPCconcentrationsin abioticmedia. Guiding the estimationofrisksaretwotypesof endpoints:(1)assessmentendpointsand(2)measurementendpoints.Theseendpointsarediscussedin Sections2.3.1and2.3.2. Riskquestionsandhypothesesaredevelopedtotestassumptionsregardingrelationshipsbetweenselectedassessmentendpoints,measurementendpoints,andpotentialexposurestorepresentativereceptors.Theseriskquestions/hypothesesarediscussedinSection 2.3.3. Table 23 relatestheriskquestions/hypothesestoeachassessment and measurementendpoint. 2.3.1 Objectives and Assessment EndpointsAssessmentendpointsidentifythe ecologicalvaluestobeprotected.FortheOU2BERA,abundanceanddiversityofaquaticmacroinvertebratesorfishareimportantassessmentendpoints.Assessmentendpointsareusedin futurephases,suchastheFS,andintegrated intoremedialactionobjectives. Appropriate assessmentendpoints aredevelopedby riskassessorsandoftenconsiderguidancefrom relevantregulatoryagencies. BERArelated goalsand objectivesinclude: Reestablishment or maintenance of a balanced and diverse aquaticecosystem adjacenttoand downstreamoftheFormosa Mine. - TheaquaticecosystemsofMiddleCreekandSouth ForkMiddleCreekareadverselyaffectedbyCOPCsreleasedfrom OU1.Historicalandrecentecologicalinvestigationshaveidentifieda spatial zoneof impairmentinthesesurfacewaters thatextendsdownstreamoftheupperreachesevaluatedin theOU1 RI(CDM2012).ThisisdescribedfurtherinSections5.2and5.3.3.

- Thisgoalincludesaspatial componentwherethezoneofimpairment,ascurrentlyunderstoodfrompreviousinvestigations, will be reducedinsizesothatazoneofrecoverybecomesapparentatlocationsclosertothecurrentsourceareasofOU1(i.e.,suitable

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conditionsareextendedupstream).Thezone of impairmentis definedbyreducedabundanceanddiversityofBMIandotheraquatic liferelative toanearbyreferenceareaunimpactedbyminerelatedcontamination.

Reestablishmentofaquaticecosystems downstreamoftheFormosaMinesuitablefor

supportingallrelevant life stagesofhistoricalsalmonidspecies. - Similartothe abovegoal,thisgoal includesa spatialcomponentwherethezone ofimpairment,ascurrentlyunderstood,willbereducedinsizeso thata zoneof recoverybecomesapparentatlocationsclosertothecurrentMIWsource areas(i.e.,suitableconditionsareextendedupstream).Thezone of impairmentis definedbyreduced abundanceoffish, especiallysalmonids,relativetoanearbyreferenceareaunimpactedbyminerelatedcontamination.Achievementofthis goal may be assessedbymeasuringfishabundanceaswellasincreased evidence ofreproduction(e.g., presenceofyoungoftheyearfish,numberofredds[i.e.,nests])relativetocurrentconditions.

TheOU2BERAisdesignedtosupportdecisionsrelatedtoremedial action goalsand objectives. Thissupportconsistsofselectingappropriateassessmentendpoints andevaluatingrisksrelatedtotheseendpoints.Riskevaluation andinterpretationisguidedbydevelopmentofspecificriskquestionsor hypotheses.Thereceptors andhabitats,contaminantsofconcern,toxicmechanisms,andexposurepathwayswereusedtoselectthe followingassessmentendpoints. Implicit in theseassessment endpointstatementsisthe conceptofensuringthatthesevaluesorresourceswarrantprotectionorshouldbereestablished or maintained. 2.3.1.1 Surface Water Based Assessment Endpoints Protectionofaquatic life,including aquaticplants,watercolumnandBMI, fish,andlarval amphibians,fromthetoxiceffects,onsurvival,growth,andreproduction,ofCOPCspresentin surfacewater

Protectionoffishpopulationsandcommunities,especiallysalmonids, with potentialtooccurinandinsomecasesreproduceinaquaticenvironmentsofinterest tothisBERA - Protectindividualsoffederallylistedspecies,including federallythreatenedOregoncoast cohosalmon

2.3.2 Measurement EndpointsAssessmentendpointsareoftendifficult tomeasureorevaluate directly.Forexample,itcannotbe predictedwithcertaintytheconditionsnecessarytoensurethe survivalandsuccessfulreproductionoffish in surfacewatersadjacenttoordownstreamofthemine,asthisdependsoninnumerablefactors.However,toxicitydatabased onexperimentalstudiesorthosedesignatedascriticalthresholdsbyregulatoryagenciesoftencan helppredictthelikelyoutcomeofexpectedexposures.Measurementendpoints areforthemostpart TRVsselectedfrom orbasedonacceptedsourcessuchasEPAandotherrelevantregulatoryagencies.Section4ofthe OU2 BERA presentsthesurfacewaterspecificTRVs selectedforestimatingriskstoecologicalreceptors. Measurementendpointsareused whereassessment endpointscannotbedirectlymeasuredorevaluated.Measurementendpoints arequantitativeexpressionsofobservedormeasuredbiologicalresponses tostressorsrelevantto selectedassessmentendpoints.Forexample,survival andgrowthof aquaticinvertebrates(anassessmentendpoint)canbeevaluated using aquatic toxicitydata basedon

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anappropriatemeasurementendpoint. Asa morespecificexample,concentrationsofmetalsinsurfacewater canbecomparedto concentrationsinlaboratorytestswithsurfacewaterthatresultedinobservedecologicallysignificanteffectstosensitiveandrelevanttestspecies (i.e.,thewaterflea[Ceriodaphnia dubia]).Thisexampleexpressestherelationshipbetweenarelevant measurementendpoint(chroniceffectsconcentration ofmetals in surface water)thatisdirectlyrelatedtotheassessmentendpointsofaquatic invertebrate survivalandgrowth.Measurementendpointsselected fortheOU2BERAincludeinformation from appropriate aquatic ecotoxicitystudiesandwaterqualitystudiesand,wheredataallow,sitespecificbiologicaldata. FortheOU2BERA,ecologicallysignificanteffectsaredefined as thoseaffecting survival,growth, orreproduction ofselectedreceptors.Otherendpoints,suchaseffectsonbehavior orhistopathologicaleffects,are notconsideredbecausethesecannot beeasilylinkedtoecologically significantendpoints that can impair populations or communities.Protectionof populationsandcommunitiesisamajorgoal oftheOU2BERA whileprotectionofindividual organismsiswarrantedforfederallylisted speciesandspeciesofconcern. 2.3.3 Risk Questions/HypothesesHypothesesorriskquestionsareusedtotestassumptionsregardingrelationshipsbetweenselectedassessmentendpoints,measurementendpoints,and potential exposuresforselectedrepresentativereceptors.ThehypothesesidentifiedfortheOU2BERAarebased ontheselectedecologicalreceptors andthemajorexposure scenarioslinked to thesereceptors.Somereceptorgroups,although consideredimportant,arenotincluded inthefollowinghypothesesbecauseassessmentdataare sparseorlacking. Forexample, protectionof localamphibianpopulationsisconsideredimportant,butdataarelackingtoassessthepotentialimpactsonthesereceptors.Agoalofthe OU2BERAis toanswerthefollowingriskquestionswithsufficient confidence toallow appropriatedecisionmaking withregardtoremediation. BenthicMacroinvertebrates Arethelevelsofcontaminantsinsurface watergreaterthanthesurfacewaterTRVsor surrogatevaluesforthesurvival,growth,orreproductionof BMI? - Datatosupportaresponsetothis questioninclude COPC as dissolvedconcentrationsinsurfacewater thatarehardness adjusted, as applicable, from multiplelocationsimmediatelydowngradientfromtheFormosaMineSite,wherehabitatsarenonsupportiveofBMI,todownstreamlocationswhereBMIhabitatshaverecoveredtonearreferenceconditions.

Isthestructure(basedprimarily onabundanceanddiversity)ofBMIcommunitiessignificantlydifferentfromreferencelocations? - Datatosupportaresponsetothis questioninclude historical andrecentBMIsurveysconductedfortheOU2BERA,emphasizingmeasurementofmetrics relatedtoabundanceanddiversityfromlocationsincludingreferenceandpotentiallyimpairedreflectingconditionsbetweenhighlyimpaired(i.e.,currentlynonsupportiveofBMI)andreference.

AquaticLife(General) Aretheconcentrationsofdissolvedcontaminantsin surfacewater within theaquatic ecosystemsofOU2greater thanthesurfacewaterTRVs(dissolved) forthesurvival,growth,

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andreproductionof aquatic life, including aquaticplants,watercolumn andBMI, fish, and larval amphibians? - Datatosupportaresponsetothis questioninclude COPC as dissolvedconcentrationsinsurfacewater thatarehardness adjusted, as applicable, from multiplelocationsimmediately downgradientfromtheFormosaMineSite,wherehabitatsarenonsupportiveofaquaticlife,todownstream locationswhereaquatichabitats haverecovered tonearreferenceconditions.

Fish Aretheconcentrationsofdissolvedcontaminantsin surfacewater greaterthanthedissolved surfacewater TRVsforthesurvival,growth,and reproductionof fish,witha focuson salmonid fish? - Datatosupportaresponsetothis questioninclude COPC as dissolvedconcentrationsinsurfacewater thatarehardness adjusted, as applicable, from multiplelocationsimmediatelydowngradientfromtheFormosaMineSite,wherehabitatsarenonsupportiveoffish,towherepotentialfish habitatshaveapparentlyrecovered tonearreference conditions.

Isthereadifferenceinfishpresence/absenceinsurfacewatersaffectedbyMIWcompared toreferenceareas? - Datatosupportaresponsetothisquestioninclude fishsurveysemphasizingpresence/absenceandgeneralnumbersandtypesofspeciesrelativetoreference.ReferenceisdefinedhereaslocationsdownstreamofOU1where abundanceanddiversityoffishapproachvaluesexpected fornonimpairedwatersinthisregion.Surveylocations encompassareasofsevere impairment(i.e.,upstreamlocations currentlynonsupportiveoffish)andreferenceareas. Multiple locationswithintheseboundariesweresurveyedtoprovidecharacterizationofthe currenttransitionalzonebetweensevereimpairmentandrecovery.Samplinglocations,methods,and,totheextentpossible,agencies/firms/staffusedinprevioussurveyswereconsistenttoallowforcomparabilityovertime (notethatadversesituationsrelatedtoattainmentofcollection permits were minimizedusingthisapproach).

Table 23 summarizesthe relationshipbetweenassessmentendpoints,representativereceptorspecies,measurementendpoints,andthe associatedriskquestions(i.e.,testablehypotheses).

2.4 Conceptual Site ModelTheCSMfor theOU2BERA(Figure 21) isa visualpresentationthatsummarizeskeycomponents relatedtopotentialecologicalexposures resultingfromsiterelated chemical contamination.The CSM istheprimaryoutputofthe ProblemFormulation phaseoftheecologicalriskassessment.Itsummarizesexposurescenariosand isusedtohelpdevelopaseriesoftestablenullhypotheses,aspresentedinthissection.Inaddition,theCSM is usedtosupporttheselectionofappropriateassessmentandmeasurementendpoints. TheCSMpresentsthepotentialexposurepathwaysforrepresentativeecologicalreceptorsexposedtominerelatedcontaminants.Tobe comprehensive, theCSMincludeshumanhealth exposurepathwaysalthoughtheyarenotdiscussed furtherin theOU2BERA.These potentialpathwaysindicatehowthe

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ecologicalresourcescancooccurorcomeincontactwithcontaminantsandincludecontaminant sources, fate and transport processes,andexposureroutes. FortheOU2BERA, Figure 21 presents allthecomponentsoftheCSM.Includedonthisfigurearesymbolsrepresentingvariousassumptionsaboutexposurepathways.Solidcirclesrepresentcompleteandsignificantexposurepathwaysthatare evaluated quantitatively.Opencirclesrepresentincompleteexposurepathways.Blacktrianglesrepresentexposurepathwaysthatareconsideredoneofthefollowing: Insignificant andcomplete(subjecttoqualitativeevaluationwhere data allow) Insignificantandcomplete(but notevaluatedduetolackofdata) Potentiallycompletebutinsignificantor highly unlikely in mostcases

Quantitativeriskestimationin theOU2BERAisreservedforthefollowing: Aquaticbenthicinvertebratesbasedoninstreamsurfacewaterexposures Fishandwatercolumninvertebratesand,toalesserextent,aquaticplantsandlarval

amphibiansbasedonsurfacewaterexposures

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Table 21 Wildlife and Plants Found at the Formosa Mine OU2 and Vicinity Douglas County, Oregon

Scientific Name Observed? Notes*

Birds Bandtailed pigeon Patagioenas fasciata Yes Blackcapped chickadee Poecile atricapilla Yes Bushtit Psaltriparus minimus Yes Common raven Corvus corax Yes Greathorned owl Bubo virginianus heard only Mountain quail Oreortyx pictus Yes Northern Spotted Owl Strix occidentalis caurina No Likely to occur Redbreasted nuthatch Sitta canadensis Yes Redtailed hawk Buteo jamaicensis Yes Rufous hummingbird Selaphorus rufus Yes Steller's jay Cyanocitta stelleri Yes Turkey vulture Cathartes aura Yes Violetgreen swallow Tachycineta thalassina Yes Western screetch owl Megascops kennicotti Yes Wrentit Chamaea fasciata heard only Mammals

American black bear Ursus americanus Yes Bobcat Lynx rufus sign Coyote Canis latrans sign Mountain lion Felis concolor No Likely to occur in low numbers Mule (blacktailed) deer Odocoileus hemionus Yes Roosevelt elk Cervus canadensis roosevelti Yes Western gray squirrel Sciurus griseus Yes Woodrat Neotoma sp. Yes Fish

Black crappie Pomoxis nigromaculatus No Likely to occur in lower watershed Bluegill Lepomis macrochirus No Likely to occur in lower watershed Brown bullhead Ameiurus nebulosus No Likely to occur in lower watershed Chinook salmon Oncorhynchus tshawytscha No Likely to occur in lower watershed Coarsescale sucker Catostomus macrocheilus No Likely to occur in lower watershed Coho salmon Oncorhynchus kisutch Yes Cutthroat trout Oncorhynchus clarki Yes Longnose dace Rhinichthys cataractae dulcis No Likely to occur in lower watershed Pacific lamprey Lampetra tridentata No Likely to occur in lower watershed Rainbow trout Oncorhynchus mykiss Yes Redside shiner Richardsonius balteatus hydrophlox No Likely to occur in lower watershed River lamprey Lampetra ayresi No Likely to occur in lower watershed Salmon Unknown Yes

Sculpin Cottus spp. Yes Smallmouth bass Micropterus dolomieu No Likely to occur in lower watershed Speckled dace Rhinichthys osculus No Likely to occur in lower watershed Umpqua pikeminnow Ptychocheilus oregonensis No Likely to occur in lower watershed


Table 21 Wildlife and Plants Found at the Formosa Mine OU2 and Vicinity Douglas County, Oregon

Scientific Name Observed? Notes*

Reptiles and Amphibians

Common garter snake Thamnophis sirtalis Yes Pacific giant salamander Dicamptodon ensatus Yes Pacific chorus (tree) frog Pseudacris regilla No Likely to occur Roughskinned newt Taricha granulosa Yes Rubber boa Charina bottae Yes Western fence lizard Sceloporus occidentalis Yes Western skink Eumeces skiltonianus Yes Hibernaculum found during sampling Invertebrates Benthic invertebrates Multiple Taxa Yes

Ground beetle Family Carabidae Yes

Lorquin's admiral butterfly Limenitis lorquini Yes Water striders (skimmers) Family Gerridae Yes

Yellowspotted millipede Harpaphe haydeniana Yes Trees

Bigleaf maple Acer macrophyllum Yes

Black cottonwood Populus trichocarpa Yes California black oak Quercus kelloggii Yes Canyon live oak Quercus chrysolepis Yes Douglasfir Pseudotsuga menziesii Yes Golden chinkapin Chrysolepis chrysophylla Yes Incense cedar Calocedrus decurrens Yes Jeffrey pine Pinus jeffreyi Yes Oregon ash Fraxinus latifolia Yes Oregon myrtle Umbellularia californica Yes Oregon white oak Quercus garryana Yes Pacific madrone Arbutus menziesii Yes Ponderosa pine Pinus ponderosa Yes Red alder Alnus rubra Yes Sugar pine Pinus lambertiana Yes Tan oak Lithocarpus densiflorus Yes Vine maple Acer circinatum Yes Western hemlock Tsuga heterophylla Yes Western redcedar Thuja plicata Yes Willow Salix sp. Yes Shrubs

Manzanita Arctostaphylos sp. Yes Oregon grape Mahonia aquifolium Yes Western poison oak Toxicodendron diversilobum Yes Salal Gaultheria shallon Yes Western sword fern Polystichum munitum Yes Thimbleberry Rubus parviflorus Yes Wedgeleaf ceanothus Ceanothus cuneatus Yes

*Likely to occur based on habitat and range.


Table 22 Federally Listed, Candidate Species, and Species of Concern and Potential to Occur at the Formosa Mine OU2 and Vicinity Douglas County, Oregon Common Name Scientific Name Listing Status Potential to Occur1

Birds

Acorn woodpecker Melanerpes formicivorus SC Low American Peregrine falcon Falco peregrinus anatum DL Low Bald eagle Haliaeetus leucocephalus DL Low Bandtailed pigeon Patagioenas fasciata SC High Black oystercatcher Haematopus bachmani SC None Brown pelican Pelecanus occidentalis DL None Harlequin duck Histrionicus histrionicus SC Low Lewis' woodpecker Melanerpes lewis SC Low Marbled murrelet Brachyramphus marmoratus CH FT Low Mountain quail Oreortyx pictus SC High Northern goshawk Accipiter gentilis SC Moderate Northern spotted owl Strix occidentalis caurina CH FT High Olivesided flycatcher Contopus cooperi SC Moderate Oregon vesper sparrow Pooecetes gramineus affinis SC Low Purple martin Progne subis SC Low Shorttailed albatross Phoebastria albatrus FE None Western burrowing owl Athene cunicularia hypugaea SC None Western snowy (coastal) plover Charadrius alexandrinus nivosus CH FT None Whiteheaded woodpecker Picoides albolarvatus SC Low Yellowbreasted chat Icteria virens SC Low Mammals

Fisher Martes pennanti Candidate Moderate Fringed myotis bat Myotis thysanodes SC Moderate Longeared myotis bat Myotis evotis SC Moderate Longlegged myotis bat Myotis volans SC Moderate Pallid bat Antrozous pallidus pacificus SC Low Red tree vole Arborimus longicaudus Candidate Moderate Silverhaired bat Lasionycteris noctivagans SC Moderate Smallfooted myotis bat Myotis ciliolabrum SC Moderate Townsend's western bigeared bat Corynorhinus townsendii townsendii SC Moderate Whitefooted vole Arborimus albipes SC Moderate Yuma myotis bat Myotis yumanensis SC Moderate Fish

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