Attachment 3 Final Mitigated Negative Declaration — Thousand Oaks City Council, March 25, 2025 (part 2 of 2)

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Appendix A Photo Documentation

APPENDIX A / PHOTO DOCUMENTATION
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Photo1.Portion of habitat proposed for the debris basin. Photo oriented west. February 8, 2021Photo2.Oak trees upslope from the ephemeral channel. Photo oriented northeast. February 8, 2021Photo3.View of location proposed for the debris basin. Photo oriented southwest. February 17, 2021Photo4.Ephemeral channel downslope from oak trees shown in Photo 2. Photo oriented southeast. February 8, 2021.

APPENDIX A / PHOTO DOCUMENTATION
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Photo5.Ephemeral channel within and near the southeast edge of the BSA. Photo oriented southeast. February 8, 2021Photo6.Manhole work location. Photo oriented east. February 8, 2021. Photo7.Concrete v-ditch and drain along the existing treatment plant. Photo oriented west.March 21, 2022. Photo8.Concrete v-ditch and drain along the existing treatment plant. Photo oriented north.March 21, 2022. .

APPENDIX A / PHOTO DOCUMENTATION
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Photo9.Swale (1-foot width) located near the western edge of the BSA. Photo oriented north.March 21, 2022Photo10.Wetland Sampling Point Swale-01. Photo oriented southeast. March 21, 2022.

Photo11.Wetland Sampling Point Ephemeral-01. Photo oriented southeast. March 21, 2022.. Photo12.Conejo dudleya (Dudleya parva) located uphill from the proposed debris basin June 24, 2022

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Appendix B Data Forms

Appendix C Photo Documentation

APPENDIX C / PHOTO DOCUMENTATION
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Photo1.Portion of habitat proposed for the debris basin. Photo oriented west. February 8, 2021. Photo2.Oak trees upslope from the ephemeral channel. Photo oriented northeast. February 8, 2021Photo3.View of location proposed for the debris basin. Photo oriented southwest. February 17, 2021Photo4.Ephemeral channel downslope from oak trees shown in Photo 2. Photo oriented southeast. February 8, 2021.

APPENDIX C / PHOTO DOCUMENTATION
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Photo5.Ephemeral channel within and near the southeast edge of the BSA. Photo oriented southeast. February 8, 2021Photo6.Manhole work location. Photo oriented east. February 8, 2021. Photo7.Concrete v-ditch and drain along the existing treatment plant. Photo oriented west.March 21, 2022. Photo8.Concrete v-ditch and drain along the existing treatment plant. Photo oriented north.March 21, 2022.

APPENDIX C / PHOTO DOCUMENTATION
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Photo9.Swale (1-foot width) located near the western edge of the BSA. Photo oriented north.March 21, 2022. Photo10.Wetland Sampling Point Swale-01. Photo oriented southeast. March 21, 2022.

Photo11.Wetland Sampling Point Ephemeral-01. Photo oriented southeast. March 21, 2022.. Photo12.Conejo dudleya (Dudleya parva) located uphill from the proposed debris basin June 24, 2022

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Appendix D Plant and Wildlife Species Observed

APPENDIX D / PLANT AND WILDLIFE SPECIES OBSERVED
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Plant SpeciesDicotsADOXACEAEMUSKROOTFAMILYSambucus mexicanablue elderberryAMARANTHACEAEAMARANTHFAMILY*Amaranthus albusprostrate pigweedANACARDIACEAESUMACORCASHEWFAMILYRhus integrifolialemonade berry*Schinus mollePeruvian peppertree*Schinus terebinthifoliusBrazilian peppertreeToxicodendron diversilobumpoison oakAPIACEAECARROTFAMILYBowlesia incanahoary bowlesiaAPOCYNACEAEDOGBANEFAMILY*Nerium oleanderoleanderASTERACEAESUNFLOWERFAMILYAcourtia microcephalasacapelloteArtemisia californicaCalifornia sagebrushBaccharis pilulariscoyote brushBrickellia californicaCalifornia brickellbush*Carduus pycnocephalusssp. pycnocephalusItalian plumeless thistle*Centaurea melitensisMaltese star-thistleCorethrogyne filaginifoliasand-asterEncelia californicaCalifornia brittle bush*Erigeron bonariensisasthmaweedEriophyllum confertiflorumvar. confertiflorumgolden-yarrowLasthenia gracilisneedle goldfieldsMalacothrix saxatilisvar. commutatacliff desertdandelionPseudognaphalium californicumladiestobaccoRafinesquia californicaCalifornia plumeseed*Senecio vulgarisold-man-in-the-Spring*Silybum marianumblessed milkthistle* Sonchus asperspiny sowthistle

APPENDIX D / PLANT AND WILDLIFE SPECIES OBSERVED
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Stephanomeria virgatarod wirelettuceUropappus lindleyiLindleys silverpuffsBORAGINACEAEBORAGEFAMILYAmsinckia menziesiiMenziesfiddleneckCryptantha intermediavar. intermediaClearwater cryptanthaEmmenanthe pendulifloravar. penduliflorawhisperingbellsEucrypta chrysanthemifoliavar. chrysanthemifoliaspotted hideseedPhacelia cicutariavar. hispidacaterpillar phaceliaPholistoma auritumvar. auritumblue fiestaflowerBRASSICACEAEMUSTARDFAMILY*Brassica nigrablack mustard*Capsella bursa-pastorisshepherds purse*Hirschfeldia incanashortpod mustard*Sisymbrium orientaleIndian hedgemustardThysanocarpus laciniatusmountain fringepodCACTACEAECACTUSFAMILYOpuntia littoraliscoast prickly pearCAPRIFOLIACEAEHONEYSUCKLEFAMILYLonicera subspicatavar. denudataSanta Barbara honeysuckleCARYOPHYLLACEAEPINKFAMILY*Stellaria mediacommon chickweedCHENOPODIACEAEGOOSEFOOTFAMILY*Atriplex semibaccataAustralian saltbushChenopodium californicumCalifornia goosefoot*Salsola tragusprickly Russian thistleCONVOLVULACEAEMORNING-GLORYFAMILYCalystegia macrostegiassp. intermediaisland false bindweed*Convolvulus arvensisfield bindweedCRASSULACEAESTONECROPFAMILYDudleya lanceolatalanceleaf liveforeverDudleya parvaConejo dudleyaCUCURBITACEAEGOURDFAMILYMarah macrocarpaCucamonga manroot

APPENDIX D / PLANT AND WILDLIFE SPECIES OBSERVED
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FABACEAELEGUMEFAMILYAcmispon glabervar. glabercommon deerweedLupinus bicolorminiature lupine*Medicago polymorphaburclover*Melilotus indicusannual yellow sweetcloverFAGACEAEOAKFAMILYQuercus agrifoliavar. agrifoliacoast live oakQuercus berberidifoliaInland scrub oak*Quercus ilexholly oakGERANIACEAEGERANIUMFAMILY*Erodium cicutariumredstem storks bill*Erodium moschatummusky storks billLAMIACEAEMINTFAMILY*Lamium amplexicaulehenbit deadnettle*Marrubium vulgarehorehoundSalvia leucophyllapurple sageSalvia melliferablack sageMALVACEAEMALLOWFAMILY*Malva parvifloracheeseweed mallowMONTIACEAEMONTIAFAMILYClaytonia perfoliataminer's lettuceClaytonia rubrassp. rubraredstem springbeautyMYRSINACEAEMYRSINEFAMILY*Lysimachia arvensisscarlet pimpernelMYRTACEAEMYRTLEFAMILY*Eucalyptus camaldulensisriver redgum*Eucalyptus polyanthemosredboxNYCTAGINACEAEFOUROCLOCKFAMILYMirabilis laevisvar. crassifoliaCalifornia four oclockONAGRACEAEEVENINGPRIMROSEFAMILYCamissoniopsis micranthaminiature suncupClarkia unguiculataelegant clarkia

APPENDIX D / PLANT AND WILDLIFE SPECIES OBSERVED
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Epilobium canumhummingbird trumpetEulobus californicusCalifornia suncupPAEONIACEAEPEONYFAMILYPaeonia californicaCalifornia peonyPHRYMACEAELOPSEEDFAMILYDiplacus aurantiacusbush monkeyflowerPLANTAGINACEAEPLANTAINFAMILYCollinsia heterophyllapurple Chinese housesKeckiella cordifoliaheartleaf keckiellaPOLEMONIACEAEPHLOXFAMILYGilia angelensischaparral giliaPOLYGONACEAEBUCKWHEATFAMILYEriogonum elongatumvar. elongatumlongstem buckwheatEriogonum fasciculatumvar. foliolosumCalifornia buckwheatPterostegia drymarioideswoodland pterostegia*Rumex crispuscurly dockRHAMNACEAEBUCKTHORNFAMILYCeanothus megacarpusvar. megacarpusbigpod ceanothusRhamnus ilicifoliahollyleaf redberryROSACEAEROSEFAMILYAdenostoma fasciculatumchamiseCercocarpus betuloidesvar. betuloidesbirchleaf mountain mahoganyHeteromeles arbutifoliatoyonPrunus ilicifoliassp. ilicifoliamainland cherryRUBIACEAEMADDERFAMILYGalium angustifoliumssp. angustifoliumnarrowleaf bedstrawGalium aparinestickywillySOLANACEAENIGHTSHADEFAMILY*Nicotiana glaucatree tobaccoSolanum xantiPurple nightshadeURTICACEAENETTLEFAMILYParietaria hesperarillita pellitory*Urtica urensdwarf nettle

APPENDIX D / PLANT AND WILDLIFE SPECIES OBSERVED
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Ferns and Fern AlliesPOLYPODIACEAEPOLYPODYFAMILYPolypodium californicumCalifornia polypodyPTERIDACEAEBRAKEFAMILYPellaea andromedifoliacoffee cliffbrakePentagramma triangularisssp. triangularisgoldback fernSELAGINELLACEAESPIKE-MOSSFAMILYSelaginella bigeloviibushy spikemossMonocotsAGAVACEAEAGAVEFAMILYHesperoyucca whippleichaparral yuccaLILIACEAELILYFAMILYFritillaria bifloravar. biflorachocolate lilyPOACEAEGRASSFAMILY*Avena barbataslender oat*Bromus diandrusripgut brome*Bromus hordeaceussoft brome*Bromus madritensiscompact brome*Bromus rubensred bromeElymus condensatusgiant wild rye*Festuca myurosrat-tail fescue*Lamarckia aureagoldentop grassMelica imperfectasmallflower melicgrass*Schismus barbatuscommon Mediterranean grassStipa lepidafoothill needlegrassTHEMIDACEAEBRODIAEAFAMILYDipterostemon capitatusssp. capitatusbluedickssignifies introduced (non-native) species

APPENDIX D / PLANT AND WILDLIFE SPECIES OBSERVED
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Wildlife SpeciesReptilesPHRYNOSOMATIDAEIGUANIDLIZARDSSceloporus occidentaliswestern fence lizard (possible)BirdsACCIPITRIDAEHAWKS,KITES,EAGLES,ANDALLIESButeo jamaicensisred-tailed hawkAEGITHALIDAELONG-TAILEDTITSANDBUSHTITSPsaltriparus minimusbushtitCATHARTIDAENEWWORLDVULTURESCathartes auraturkey vultureCHARADRIIDAELAPWINGSANDPLOVERSCharadrius vociferuskilldeerCORVIDAECROWSANDJAYSAphelocoma californicaCalifornia scrub-jayCorvus brachyrhynchosAmerican crowFRINGILLIDAEFRINGILLINEANDCARDUELINEFINCHESANDALLIESHaemorhous mexicanushouse finchMIMIDAEMOCKINGBIRDSANDTHRASHERSToxostoma redivivumCalifornia thrasherPARIDAECHICKADEESANDTITMICEBaeolophus inornatusoak titmousePASSERELLIDAENEWWORLDSPARROWSJunco hyemalisdark-eyed juncoMelozone crissalisCalifornia towheeZonotrichia leucophryswhite-crowned sparrowPICIDAEWOODPECKERSANDALLIESDryobates nuttalliiNuttalls woodpecker

APPENDIX D / PLANT AND WILDLIFE SPECIES OBSERVED
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POLIOPTILIDAEGNATCATCHERSPolioptila caeruleablue-gray gnatcatcherREGULIDAEKINGLETSRegulus calendularuby-crowned kingletSYLVIIDAESYLVIIDWARBLERSChamaea fasciatawrentitTROCHILIDAEHUMMINGBIRDSCalypte annaAnnas hummingbirdTROGLODYTIDAEWRENSTroglodytes aedonhouse wrenMammalsCRICETIDAERATS,MICE,ANDVOLESNeotoma sp.woodrat (middens)SCIURIDAESQUIRRELSSpermophilus (Otospermophilus) beecheyiCalifornia ground squirrel

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Appendix E Special-Status Plant Species Not Expected or with Low Potential to Occur

APPENDIX E / SPECIAL-STATUS PLANT SPECIES NOT EXPECTED OR WITH LOW POTENTIAL TO OCCUR 12767E-13MARCH 2023
FE: Federally listed as endangeredFT: Federally listed as threatenedSE: State listed as endangeredSR: State Rare California Rare Plant RankCRPR 1B: Plants rare, threatened, or endangered in California and elsewhereCRPR 2B: Plants rare, threatened, or endangered in California but more common elsewhereCRPR 3: Review List: Plants about which more information is neededCRPR 4: Watch List: Plants of limited distribution.1 Seriously threatened in California (over 80% of occurrences threatened / high degree and immediacy of threat).2 Moderately threatened in California (2080% occurrences threatened / moderate degree and immediacy of threat).3 Not very threatened in California (<20% of occurrences threatened / low degree and immediacy of threat or no currentthreats known)ReferencesCalflora. 2022. CDFW (California Department of Fish and Wildlife). 2022a. California Natural Diversity Database (CNDDB). RareFind 5.2.14 (Commercial Subscription). Sacramento, California: CDFW, Biogeographic Data Branch. https://map.dfg.ca.gov/rarefind/view/RareFind.aspx.CDFW. 2022b. Special Vascular Plants, Bryophytes, and Lichens List. California Department of Fish and Wildlife. Sacramento, California. July 2022. https://www.dfg.ca.gov/wildlife/nongame/list.html.

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Appendix F CDFW CNDDB Form

Appendix G Special-Status Wildlife Species with Low Potential or Not Expected to Occur

APPENDIX G / SPECIAL-STATUS WILDLIFE SPECIES NOT EXPECTED OR WITH LOW POTENTIAL TO OCCUR 12767G-11MARCH 2023
ReferencesCDFW (California Department of Fish and Wildlife). 2022a. California Natural Diversity Database (CNDDB). RareFind 5.2.14 (Commercial Subscription). Sacramento, California: CDFW, Biogeographic Data Branch. https://map.dfg.ca.gov/rarefind/view/RareFind.aspx.CDFW. 2022b. CalDatabase. CDFW, Biogeographic Data Branch. July 2022. https://www.dfg.ca.gov/wildlife/nongame/list.html.eBird. 2021. eBird: An online database of bird distribution and abundance [web application]. eBird, Cornell Lab of Ornithology, Ithaca, New York. Available: http://www.ebird.org.

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Appendix B2 Aquatic Resources Delineation Report

MARCH 2023Prepared for:CITY OF THOUSAND OAKS2100 E. Thousand Oaks BoulevardThousand Oaks, California 91362Contact: Nader HeydariPrepared by:621 Chapala StreetSanta Barbara, California 93101Contact: Melissa [email protected]

Printed on 30% post-consumer recycled material.

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Table of ContentsSECTION PAGE NO.Acronyms and Abbreviations............................................................................................................................................ iii1 Introduction ..........................................................................................................................................................11.1 Disclaimer Statement ............................................................................................................................11.2 Contact Information ...............................................................................................................................12 Site Description and Landscape Setting ............................................................................................................12.1 Soils.........................................................................................................................................................22.2 Vegetation...............................................................................................................................................22.3 Watershed...............................................................................................................................................22.4 National Wetland Inventory ...................................................................................................................33 Aquatic Resources Delineation Methods ...........................................................................................................34 Aquatic Resources Narrative...............................................................................................................................44.1 Waters of the United States...................................................................................................................54.2 Waters of the State ................................................................................................................................55 Results and Conclusions .....................................................................................................................................76 References Cited..................................................................................................................................................8TABLES1 Applicant and Agent Contact Information...........................................................................................................12 Schedule of the Aquatic Resources Delineation...................................................................................................33 RWQCB Aquatic Resource Summary for the Biological Survey Area ................................................................64 CDFW Aquatic Resource Summary for the Biological Survey Area ...................................................................6FIGURES1 Project Location ...................................................................................................................................................92 Soils .............................................................................................................................................................. 113 Hydrologic Setting ............................................................................................................................................. 134 Potential Jurisdictional Aquatic Resources ..................................................................................................... 15APPENDICESA Photo DocumentationB Data Forms

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Acronyms and AbbreviationsAcronym/AbbreviationDefinitionCDFW California Department of Fish and WildlifeOHWM ordinary high-water markProject Hill Canyon Treatment Plant Stormwater Diversion ProjectRWQCB Regional Water Quality Control BoardUSACE U.S. Army Corps of Engineers

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127671MARCH 2023
1 IntroductionThis Aquatic Resources Delineation Report is being prepared for the City of Thousand Oaks for the Hill Canyon Treatment Plant Stormwater Diversion Project (Project). The delineation was performed to identify and map existing aquatic resources potentially subject to the regulatory jurisdiction of the U.S. Army Corps of Engineers (USACE) pursuant to Section 404 of the Clean Water Act (33 USC 1344); Regional Water Quality Control Board (RWQCB) pursuant to Section 401 of the Clean Water Act and the Porter-Cologne Water Quality Control Act; and/or California Department of Fish and Wildlife (CDFW) pursuant to Section 1602 of the California Fish and Game Code (collectively defined as jurisdictional aquatic resources).1.1 Disclaimer StatementThis reporRWQCB, and CDFW (i.e., regulatory agencies) within the Project site using the current regulations, written policies, and guidance from these regulatory agencies. The potential jurisdictional boundaries described in this report are subject to verification by the regulatory agencies. Only the regulatory agencies can make a final determination on whether the features present are subject to USACE, RWQCB, and/or CDFW regulation. 1.2 Contact InformationContact information for the Project applicant and agent are provided in Table 1. Access to the Project site is not restricted, but if a site visit is requested, the Project applicant or agent will accompany regulatory staff to the Project site. City of Thousand Oaks is the Project applicant and landowner. Table 1. Applicant and Agent Contact InformationApplicantCity of Thousand OaksAgentPhoenix Civil EngineeringContactNameNader HeydariContactNameJon TurnerAddress2100 E. Thousand Oaks BoulevardThousand Oaks, California 91362Address535 E. Main Street Santa Paula, California 93060Phone805.449.2392Phone805.658.6800FaxNAFaxNAEmailnheydari@[email protected] Site Description and Landscape SettingThe Hill Canyon Treatment Plant (552-013-001 and 667-012-017) is located at 9600 Santa Rosa Road, Thousand Oaks, California (Figure 1, Project Location). The Project site is located within U.S. Geological Survey 7.5-minute Newberry Park quadrangle, Section 00 of Township 2 North and Range 20 West; the approximate center of the Project site is longitude 34°1239.00118°5516.02

HILL CANYON TREATMENT PLANT STORMWATER DIVERSION PROJECT / AQUATIC RESOURCES DELINEATION REPORT 127672MARCH 2023
(34.210832;118.921117). To drive to the Project site from Camarillo, take Santa Rosa Road east and turn right onto Hill Canyon Road, which will take you to the entrance of Hill Canyon Treatment Plant. The Project site is located between two publicly owned open space systems including Wildwood Regional Park, approximately 1,765 acres, and Conejo Canyons Open Space, approximately 1,430 acres. As a result, the surrounding area is predominantly open space with residential and commercial properties approximately 0.25 miles south and east of the site.A Biological Survey Area (BSA) was considered as the review area for this Project site. The BSA includes the proposed Project impact areas (Project site) and a 100-foot buffer. Topography within the BSA is variable, characterized by moderately steep slopes that lead down towards a vegetated canyon containing a linear aquatic feature. Thisunnamed feature originates southeast of the site within Wildwood Regional Park. Elevation ranges from approximately 280 feet above mean sea level in the southwestern portion of the BSA (near the manhole work area)to 400 feet above mean sea level south of the proposed debris basin. 2.1 SoilsSoil types within and surrounding the BSA are shown on Figure 2. As shown on Figure 2, soils within the natural landscapes of the BSA consist mainly of Hambright very rocky loam (HaG; 15% to 75% slopes), a shallow, well-drained soil which typically occurs on plateaus, basalt flows, and hillslopes (USDA-NRCS 2022a). Vina gravelly loam (VnC; 2% to 9% slopes) occurs along the northwestern portions of the BSA and primarily within the existing treatment plant. A third soil type, Vina loam (VaC; 2% to 9% slopes) also occurs in a portion of the existing treatment plant. The Vina soil series consists of very deep, well-drained soils (USDA-NRCS 2022a). These soils are not considered hydric soils (USDA-NRCS 2022b). 2.2 VegetationThe natural vegetated lands of the BSA are composed of a combination of vegetation communities including Chamise black sage sugarbush scrub, California brittlebrushCalifornia sagebrush scrub, lemonade berry scrub, and lemonade berry scrubCalifornia sagebrush scrub. Along with the scrub communities, mature oak trees (California black oak [Quercus kelloggii], coast/interior live oak [Q. agrifolia/wislizeni]) and scattered toyon (Heteromeles arbutifolia) and other scrub shrubs are present. In the southern portion of the BSA, near the manhole work area, California sycamorearroyo willow woodlands were mapped along Arroyo Conejo creek and non-native grasslands were present. Since the creek and majority of non-native grasslands are located outside of the BSA, only the fringes of these communities entered the edges of the BSA near the manhole work area. The scrub communities and oaks near the linear aquatic feature on site do not appear to be significantly supported by this channel, as individual oaks are present along the hillslope where the channel is not present and do not necessarily originate or line the linear aquatic feature banks (Appendix A, Photo Documentation). 2.3 WatershedThe BSA is located within the Ventura-San Gabriel Coastal basin Hydrologic Unit (180701) and Upper Conejo Arroyo subwatershed Hydrologic Unit (180701030104). The Upper Conejo Arroyo subwatershed covers an area of 27,665 acres (112 square kilometers) and encompasses the areas of Potrero Valley, Conejo Valley, and east to OakbrookRegional Park (ArcGIS 2022). See Figure 3, Hydrologic Setting.

HILL CANYON TREATMENT PLANT STORMWATER DIVERSION PROJECT / AQUATIC RESOURCES DELINEATION REPORT 127673MARCH 2023

2.4 National Wetland InventoryThe BSA contains one(USFWS 2022; see Figure 4). This resource is located along the northeastern portion of the BSA (i.e., area associated with the debris basin), originates from the undeveloped hills along the east, and travels downslope to the treatment plant. This feature is categorized as Freshwater Forested/Shrub Wetland (PSAA Cowardin classification). This categorization would suggest the presence of a wetland feature consisting of an area dominated by woody vegetation, with surface water present for brief periods of time during the growing season. 3 Aquatic Resources Delineation MethodsDudek Biologist Heather Moine conducted an aquatic resources delineation for the BSA in March 2022. Table 2summarizes the site conditions and timing of the survey. Table 2. Schedule of the Aquatic Resources Delineation DateHours1PersonnelConditions03/21/2022 9:07 a.m.5:20 p.m. Heather Moine 59°F73°F; 20%40% cloud cover;14 mph windNotes:°F = degrees Fahrenheit, mph = miles per hour.1The total site visit included aquatic resources delineation, supplemental vegetation mapping, and rare plant surveys.Jurisdictional boundaries were mapped in the field using ESRI Field Maps and a Trimble® R1 GNSS Receiver with submeter accuracy and aerial imagery. Following the fieldwork, aquatic resources were digitized using ArcGIS. The jurisdiction-specific methods used to delineate USACE, CDFW, and RWQCB are described below.Maps are included at the end of this report, including Project Location (Figure 1), Soils (Figure 2), Hydrologic Setting (Figure 3), and Potential Jurisdictional Aquatic Resources (Figure 4). U.S.ArmyCorpsofEngineersJurisdictionalDelineationMethodsThe USACE wetlands delineation was conducted in accordance with the 1987 USACE Wetlands Delineation Manual (USACE 1987) and the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (USACE 2008a). A Field Guide to the Identification of the Ordinary High Water Mark (OHWM) in the Arid West Region of the Western United States: A Delineation Manual (USACE 2008b) was used to determine the limits of non-wetland waters. Non-wetland waters were delineated on topographical maps in conjunction with ESRI Field Maps on a mobile device. The widths of each non-wetland water were determined in the field according to the OHWM manual. Wetland Determination Forms were taken at certain points within drainages or vegetation communities where a predominance of hydrophytic vegetation was present; hydrology, vegetation, and soils were assessed to determine whether USACE three-parameter wetlands were present. USACE OHWM Forms were completed at representative cross-sections of non-wetland waters to capture their characteristics and widths. Data forms can be found in Appendix B.

HILL CANYON TREATMENT PLANT STORMWATER DIVERSION PROJECT / AQUATIC RESOURCES DELINEATION REPORT 127674MARCH 2023
CaliforniaDepartmentofFishandWildlifeJurisdictionalDelineationMethodsThe delineation defined areas under the jurisdiction of the CDFW pursuant to Sections 16001603 of the California Fish and Game Code. CDFW asserts jurisdiction over rivers, streams, and lakes to the extent of the top of bank. The away from it (Vyverberg 2010). Top of bank was mapped as the physical break in slope between the channel and surrounding upland. CDFW also asserts jurisdiction over riparian vegetation associated with these features. A predominance of hydrophytic vegetation, where associated with a stream channel, was used to determine CDFW-regulated riparian areas. Streambeds under the jurisdiction of CDFW were delineated using the Cowardin method of waters classification, which defines waters boundaries by a single parameter (i.e., hydric soils, hydrophytic vegetation, or hydrology). Additionally, waters of the state were delineated based on watercourse characteristics present in the field, which include surface flow, sediment transportation and sorting, physical indicators of channel forms, channel morphology, and riparian habitat associated with a streambed.RegionalWaterQualityControlBoardJurisdictionalDelineationMethodsIn 2019, the State Water Resources Control Board issued the State Wetland Definition and Procedures for Discharges of Dredged or Fill Material to Waters of the State (SWRCB 2019). These procedures define wetlands protected under federal law, and reflects current scientific understanding of the formation and functioning of the area has continuous or recurrent saturation of the upper substrate caused by groundwater, or shallow surface water, or both; (2) the duration of such saturation is sufficient to cause anaerobic conditions in the upper substrate; and (3) the Waters of the state regulated by the RWQCB were mapped in accordance with the State Wetland Definition and Procedures for Discharges of Dredged or Fill Material to Waters of the State (SWRCB 2019). Wetland waters subject to RWQCB jurisdiction were mapped based on methods described in the 1987 Corps of Engineers Wetlands Delineation Manual (USACE 1987) and the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (USACE 2008a). Non-wetland waters subject to RWQCB jurisdiction were delineated to the extent of the top of bank and riparian vegetation, as appropriate, as described above.4 Aquatic Resources NarrativeOn March 21, 2022, Ms. Moine performed an aquatic resources delineation. Potentially jurisdictional aquatic features mapped include a concrete v-ditch, connecting swale, and an ephemeral channel (Figure 4). These features are located within and directly adjacent to the proposed debris basin. Of these features, only the ephemeral channel is anticipated to require additional permits pursuant to the Porter-Cologne Water Quality Control Act and California Fish and Game Code for impacts to the channel. However, as recommended below, written concurrence from the resource agencies (RWQCB, CDFW, and USACE) on the jurisdictional status for both features is highly recommended.

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ConcreteV-Ditch(RWQCB)The concrete v-ditch is an existing stormwater control feature within the Hill Canyon Treatment Plant that directs flows to drain-inlets along the v-ditch (Figure 4). The drain inlets are regularly maintained by Hill Canyon Treatment Plant staff as part of storm preparedness activities. These inlets capture storm flows and drain them to the sludge drying beds as part of the stormwater capture program (Capron 2017; City of Thousand Oaks 2019). Since the flows associated with the v-ditch are currently subject to the adopted Waste Discharge Requirements and National Pollutant Discharge Elimination System permits for the Hill Canyon Treatment Plant (Order No. R4-2019-0137, NPDES No. CA0056294), compliance with this existing permit should apply to this feature and further permits are not anticipated to be necessary from the RWQCB. We understand the Hill Canyon Treatment Plant had previously attained status as a zero-discharge facility. An Industrial General Permit Notice of Non-Applicability was previously granted by the RWQCB, and the City is petitioning to retain this status with site modifications to re-route off-site flows from the natural canyon and directly to Arroyo Conejo Creek (Capron 2017; City of Thousand Oaks 2019). In addition, the concrete v-ditch is unlikely to be jurisdictional to USACE under the Clean Water Act, as the feature is ephemeral and current flows lack a connection with a traditional navigable water. Similarly, the feature lacks a bed and bank often associated with CDFW jurisdictional rivers, stream, or lakes. EphemeralChannel(RWQCB/CDFW)A narrow ephemeral channel is present in the BSA within and adjacent to the proposed debris basin (Figure 4). The channel is located within the natural canyon and extends to the existing concrete v-ditch. This channel is characterized by an OHWM and a bed, with portions of the channel containing a bank. Blue elderberry (Sambucus mexicana) is present along this feature providing limited riparian habitat. In addition, a short 12-foot swale connects the feature in the eastern portion of the BSA. These features are anticipated to be jurisdictional to CDFW and the RWQCB. Given that the feature is ephemeral and lacks connection with a traditional navigable water, it is unlikely to be jurisdictional to USACE. 4.1 Waters of the United StatesAs described above, no features observed are anticipated to be Waters of the United States; and therefore, not anticipated to be under the jurisdiction of the U.S. Army Corps of Engineers. The concrete v-ditch is ephemeral and current flows lack a connection with a traditional navigable water. The ephemeral channel does not have direct connection to a traditional navigable water, is characterized by low volume or infrequent flows, and flows through this feature are directed through the existing treatment plant. 4.2 Waters of the State RegionalWaterQualityControlBoard(RWQCB)The concrete v-ditch and ephemeral channel, described above, are anticipated to be under the jurisdiction of the RWQCB. Therefore, approximately 0.04 acre (534 linear feet) of features are anticipated to be subject to regulation by the RWQCB under the Porter-Cologne Water Quality Control Act. Table 3 provides a summary of these features. However, based on existing permits only the channel is anticipated to require additional permitting for project-related activities.

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Table 3. RWQCB Aquatic Resource Summary for the Biological Survey AreaFeatureNameLocation(Latitude/Longitude;DecimalDegrees)BiologicalSurveyArea(Acres/LinearFeet)Non-WetlandWatersEphemeral channel(including top of bank)34.210854,-118.9209710.01 acre (530 square feet)219 linear feetUpland Swale 34.210701-118.920611< 0.01 (12 square feet)212 linear feetConcrete v-ditch 34.211035,-118.9210580.02 acre (758 square feet)303 linear feetRiparianBlue Elderberry (outside of ephemeral channel and bank)34.210892-118.920957< 0.01 (332 square feet)23 linear feet3Total10.04acre(1,632squarefeet)534linearfeet3Notes:1Totals may not sum due to rounding.2Swale width estimated at 1 foot. 3Riparian linear feet not included in total due to overlapping with the ephemeral channel. CaliforniaDepartmentofFishandWildlifeThe ephemeral channel described above is anticipated to be regulated by CDFW. Since CDFW regulates from bank to bank, certain portions of the BSA where the top of a channel bank extended beyond the OHWM are subject to regulation by CDFW as streambed. These areas are displayed on Figure 4. The oak trees located adjacent to the channel feature may not be jurisdictional to CDFW (but will require confirmation from CDFW). The oak trees on-site and along this channel feature do not readily appear to originate from the channel feature or appear to significantly benefit from the channel flows. The oaks near the channel originate uphill from the channel feature on upland slopes. In addition, based on the surrounding environment, oak trees are scattered throughout the upland slopes and terrain suggesting that the presence of oaks along the channel would have been present irrespective of the . Therefore, the oaks adjacent to the channel are unlikely to be categorized as riparian vegetation that is typically under CDFW jurisdiction. However, one blue elderberry plant is located along the channel and is mapped as riparian under CDFW jurisdiction.Therefore, approximately 0.02 acres (231 linear feet) of features are anticipated to be subject to regulation by the CDFW under the California Fish and Game Code Section 1600 et seq. The full extent of CDFW jurisdictional areas are those described in Table 4. Table 4. CDFW Aquatic Resource Summary for the Biological Survey AreaFeatureNameLocation(Latitude/Longitude;DecimalDegrees)BiologicalSurveyArea(Acres/LinearFeet)StreambedEphemeral channel(including top of bank)34.210854,-118.9209710.01 acre (530 square feet)219 linear feet

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Table 4. CDFW Aquatic Resource Summary for the Biological Survey AreaFeatureNameLocation(Latitude/Longitude;DecimalDegrees)BiologicalSurveyArea(Acres/LinearFeet)Upland Swale 34.210701-118.920611< 0.01 (12 square feet)212 linear feetRiparianBlue elderberry (Sambucus mexicana)34.210892,-118.9210957< 0.01 (332 square feet)23 linear feet3Total10.02acre(874squarefeet)231linearfeet3Notes:1Totals may not sum due to rounding.2Swale width estimated at 1 foot. 3Riparian linear feet not included in total due to overlapping with the ephemeral channel. 5 Results and ConclusionsBased on the jurisdictional delineation and review of relevant information provided in this Aquatic Resources Delineation Report, approximately 0.03 acres (1,300 square feet) of non-wetland waters of the state and an additional < 0.01 acre (332 square feet) of riparian habitat are potentially regulated by the RWQCB and/or CDFW. The features described in this report are not anticipated to be under the jurisdiction of the USACE. This report can be used by those agencies to determine if they would regulate the features described herein.

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6 References Citedhttps://www.arcgis.com/apps/mapviewer/index.html?layers=518ab8bc00dd4caea87d52694c7734d7.Capron, M.E. 2017. City of Thousand Oaks, Hill Canyon Wastewater Treatment Plant (HCTP), Stormwater Permit Notice of Non-Applicability via No Discharge. Dated June 27, 2017. Water Board Date Processed: July 5, 2017. City (City of Thousand Oaks). 2019. Hill Canyon Treatment Plant (HCTP) Stormwater Permit Notice of Non-Applicability via No Discharge, Amended Technical Analysis. City of Thousand Oaks, Public Works Department. File Dated October 30, 2019. SWRCB (State Water Resources Control Board). 2019. State Policy for Water Quality Control: State Wetland Definition and Procedures for Discharges of Dredged or Fill Material to Waters of the State. Adopted April 2, 2019, and revised April 6, 2021. USACE (U.S. Army Corps of Engineers). 1987. Corps of Engineers Wetlands Delineation Manual. Online ed. Environmental Laboratory, Wetlands Research Program Technical Report Y-87-1. Vicksburg, Mississippi: U.S. Army Engineer Waterways Experiment Station. January 1987. http://www.cpe.rutgers.edu/Wetlands/1987-Army-Corps-Wetlands-Delineation-Manual.pdf.USACE. 2008a. Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (Version 2.0). Environmental Laboratory, ERDC/EL TR-08-28. Vicksburg, Mississippi: U.S. Army Engineer Research and Development Center. September 2008. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1046489.pdf.USACE. 2008b. A Field Guide to the Identification of the Ordinary High Water Mark (OHWM) in the Arid West Region of the Western United States: A Delineation Manual. ERDC/CRREL TR-08-12. Prepared by R.W. Lichvar and S.M. McColley. Hanover, New Hampshire: U.S. Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory. August 2008. https://apps.dtic.mil/dtic/tr/fulltext/u2/a486603.pdf.USDA-NRCS (U.S. Department of Agriculture, Natural Resources Conservation Service). 2022a. Web Soil Survey.Accessed August 2022. https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm.USDA-NRCS. 2022bmain/soils/survey/class/.Vyverberg, K. 2010. A Review of Stream Processes and Forms in Dryland Watersheds. California Department of Fish and Wildlife. December 2010. 101
Project LocationSOURCE: Source0 2,0001,000FeetProject SiteFIGURE 1 Port HuenemeOxnardVenturaThousand OaksCamarilloMoorparkFillmoreOjaiSimi ValleyK e r n C o u n t yS a n t aB a r b a r aC o u n t yL o s A n g e l e sC o u n t yProject Site

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Appendix A Photo Documentation

Photo11.Wetland Sampling Point Ephemeral-01. Photo oriented southeast. March 21, 2022.. Photo12.Conejo dudleya (Dudleya parva) located uphill from the proposed debris basin June 24, 2022

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Appendix B Data Forms

Appendix C1 Archaeological Resources Assessment (Confidential)

Appendix C2 Built Environment Inventory and Evaluation Report

DRAFT
MAY 2022Prepared for:CITY OF THOUSAND OAKS2100 Thousand Oaks BoulevardThousand Oaks, California 91362Contact: Nader Heydari Prepared by:38 N. Marengo AvenuePasadena, California 91101Contact: Kate G. Kaiser

Printed on 30% post-consumer recycled material.

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Table of ContentsSECTION PAGE NO.Acronyms and Abbreviations............................................................................................................................................ iiiExecutive Summary ........................................................................................................................................................... v1 Introduction ..........................................................................................................................................................11.1 Project Location and Setting..................................................................................................................11.2 Project Description .................................................................................................................................11.3 Project Team...........................................................................................................................................21.4 Regulatory Setting ..................................................................................................................................21.4.1 Federal.......................................................................................................................................21.4.2 State ..........................................................................................................................................31.4.3 Local ..........................................................................................................................................61.5 Built Environment Study Area................................................................................................................72 Methods............................................................................................................................................................. 112.1 Records Search Results...................................................................................................................... 112.2 Building Development and Archival Background Research ............................................................. 152.3 Built Environment Field Methods ....................................................................................................... 173 Historical Context.............................................................................................................................................. 193.1 Early Settlement of Conejo Valley and City of Thousand Oaks......................................................... 193.2 Subject Property: Hill Canyon Treatment Plant.................................................................................. 213.3 Engineering Firm: Pomeroy & Associates (19511965) ................................................................. 244 Results of Identification and Evaluation Efforts.............................................................................................. 274.1 Property Description: Hill Canyon Treatment Plant (1961) .............................................................. 284.2 National Register of Historic Places/California Register of Historic Resources Statement of Significance................................................................................................................... 474.3 City of Thousand Oaks Significance Evaluation................................................................................. 494.4 Integrity Discussion ............................................................................................................................. 495 Summary of Findings and Management Recommendations......................................................................... 515.1 Summary of Findings .......................................................................................................................... 516 References ........................................................................................................................................................ 53 Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 2022ii
TABLES1 Property Located in Built Environment Study Area - Hill Canyon Treatment Plant Buildings and Structures......................................................................................................................................................82 Previously Recorded Cultural Resources within a 0.5-Mile Radius of the Project Site ................................ 113 Previous Technical Studies Within a 0.5-Mile Radius of the Project Site.............................................................. 134 Aerial Photographs............................................................................................................................................ 165 Hill Canyon Treatment Plant Buildings and Structures................................................................................... 28EXHIBITS1 Hill Canyon Treatment Plant facilities, the digester (left), the activated sludge unit (center), and the office/laboratory (right), under construction c. 1960. ...................................................................... 222 1967 aerial photograph of the Hill Canyon Treatment Plant taken from the MGM Studio property, view facing south. ............................................................................................................................................. 23FIGURES1 Project Location Map........................................................................................................................................ 572 Built Environment Area of Potential Effect (APE) Map.................................................................................... 59APPENDICESAB DPR Form: Hill Canyon Water Treatment Plant 12767 #CI 5427iiiMAY 2022
Acronyms and AbbreviationsAcronym/AbbreviationDefinitionACHP Advisory Council for Historic PreservationAPNNumberc. circaCEQA California Environmental Quality Actcfs cubic feet per secondCRHR California Register of Historical ResourcesMGD Million Gallons per DayNHPA National Historic Preservation Act NRHP National Register of Historic PlacesSCCIC South Central Coastal Information Center Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 2022iv

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Executive SummaryDudek was retained by City of Thousand Oaks to conduct a built environment inventory and evaluation study and report for the proposed Hill Canyon Treatment Plant Stormwater Diversion Project (Project). The Project, as proposed, will modify the existing storm drain and construct new storm drain pipes, create a new debris basin, and build a new channel to connect the debris basin and the storm drain pipes.The City of Thousand Oaks is the lead agency responsible for compliance with the California Environmental Quality Act (CEQA). The proposed Project will take place on the Hill Canyon Treatment Plant property, originally developed in 1961. Several buildings and structures at the Hill Canyon Treatment Plant property are over 45 years old and therefore the property as a whole was evaluated for historical significance, by Secretary of Interior-qualified architectural historians, in order to determine if there would be an impact to historic resources under CEQA. Efforts to identify historical resources within and adjacent to the Project site included the following components: (1) a California Historical Resources Information System records search covering the Project and a 1-mile radius around its boundary; (2) study area delineation; (3) an intensive-level survey of the study area for built environment resources; (4) archival and building development research; and (5) the evaluation of properties for the National Register of Historic Places (NRHP),California Register of Historical Resources (CRHR), and City of Thousand Oaks Landmark and Pint of Historical Interest eligibility criteria and integrity requirements. Because the Hill Canyon Treatment Plant was originally developed in 1961 and is a historic-age property, it was evaluated in accordance with the CEQA. This report concludes that the Hill Canyon Treatment Plant does not appear eligible under any NRHP, CRHR, or local City of Thousand Oaks designation criteria. Therefore, the Hill Canyon Treatment Plant is not considered a historical resource for the purposes of CEQA. This report concludes that the Project, finding under CEQA regarding built environment historical resources is no impact. The Project finding under CEQA is NoImpacttoHistoricResources. No further work is required for historic built environment properties to move forward with the Project.

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1 IntroductionThis chapter provides an overview of the proposed Hill Canyon Treatment Plant Stormwater Diversion Project (Project), qualifications of Dudek staff that prepared this report, regulatory setting, and a description of the Built Environment Study Area.1.1 Project Location and SettingThe Project site (APNs] 552-0-130-015, 520-0-300-115, and 667-0-120-170) is located at Hill Canyon Treatment Plant (Figure 1, Project Location). The address for the Treatment Plant is 9600 Santa Rosa Road, and it is located in a remote, natural canyon area, at the confluence of north and south Arroyo Conejo Creek and within the western limits of the City of Thousand Oaks in Ventura County, California. This site is located outside of the urban areas of Thousand Oaks or suburban/agricultural communities along Santa Rosa Road. The general setting of the Hill Canyon Treatment Plant is in the north fork of the Arroyo Conejo Canyon, surrounded on all sides by steep, chaparral and grass covered hills, which are part of the Conejo Canyons Open Space park, the Wildwood Regional Park, and Santa Rosa Valley Park public parks. Arroyo Conejo North Fork, a creek, runs through the middle of the treatment plant and runs first north, then turns west, then north again, winding through the canyon. 1.2 Project DescriptionThe Hill Canyon Treatment Plant, which is owned and operated by the City, provides wastewater treatment for the City of Thousand Oaks. The Treatment Plant is a 14 million gallon per day capacity wastewater treatment plant and currently treats an average of 8 million gallons of wastewater per day generated from its domestic, commercial, and industrial customers.The Treatment Plant is located at the confluence of two watersheds and experiences flooding after large storm events that exceed the capacity of some drainage facilities for conveying off-site flows. These high runoff events are followed by a subsequent cleanup and debris removal associated with run-on flows from the tributary canyons that overflow into the Treatment Plant. Under existing conditions, flows are intercepted by a concrete swale that sits behind an existing concrete masonry unit wall, directing flows to drain inlets that connect to an existing 30-inch storm drain system. Recently, the City disconnected the 30-inch storm drain from out letting off site and added a sump pump system to divert flows to an on-site basin; however, this interim solution will not be able to accommodate the 10-year storm event. The maximum capacity of the existing 30-inch storm drain is 50 cubic feet per second. The 10-year combined peak flowrate of the two watersheds is 105 cubic feet per second (cfs). The City determined that it was not feasible to increase the size of the 30-inch storm drain due to space constraints within the Treatment Plant and therefore the proposed design flow is limited to the capacity of the existing 30-inch storm drain and another design solution to intercept, capture and contain stormwater flows is necessary. Implementation of the Project would include reestablishing the existing 30--site outlet, new pipes to contain on-site flows within the site and a debris basin to contain flooding and the accompanying debris experienced after storm events associated with flows from the tributary canyons that overflow onto the Project site.

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As such, this Project proposes to modify the existing storm drain and construct new storm drain pipes, create a new debris basin, and build a new channel to connect the debris basin and the storm drain pipes. Construction of the Project, including demolition and new construction, is anticipated to occur over approximately 6 months. During and upon completion of construction, the Project would continue providing wastewater treatment services for the City. Details about each construction activity are included below.1.3 Project TeamThe Dudek Project team responsible for this report include Dudek Architectural Historian Erin Jones, MA, and Kate G. Kaiser, MSHP. The report was reviewed for quality assurance/quality control by Dudek Senior Architectural Standards (Title 36 of the Code of Federal Regulationsare located in Appendix A.1.4 Regulatory Setting1.4.1 FederalTheNationalRegisterofHistoricPlacesWhile there is no federal nexus for this Project, the subject property was evaluated in consideration of NRHP worthy of preservation. Overseen by the National Park Service, under the U.S. Department of the Interior, the NRHP was authorized under the National Historic Preservation Act, as amended. Its listings encompass all National Historic Landmarks, as well as historic areas administered by the National Park Service.NRHP guidelines for the evaluation of historic significance were developed to be flexible and to recognize the designed to guide state and local governments, federal agencies, and others in evaluating potential entries in the NRHP. For a property to be listed in or determined eligible for listing, it must be demonstrated to possess integrity and to meet at least one of the following criteria:The quality of significance in American history, architecture, archaeology, engineering, and culture is present in districts, sites, buildings, structures, and objects that possess integrity of location, design, setting, materials, workmanship, feeling, and association, and:A. That are associated with events that have made a significant contribution to the broad patterns of our history; orB. That are associated with the lives of persons significant in our past; orC. That embody the distinctive characteristics of a type, period, or method of construction, or that represent the work of a master, or that possess high artistic values, or that represent a significant and distinguishable entity whose components may lack individual distinction; orD. That have yielded, or may be likely to yield, information important in prehistory or history.

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In addition to these basic evaluation criteria, the NRHP outlines further criteria considerations for significance. Moved properties; birthplaces; cemeteries; reconstructed buildings, structures, or objects; commemorative properties; and properties that have achieved significance within the past 50 years are generally not eligible for the NRHP. The criteria considerations are exceptions to these rules, and they allow for the following types of resources to be NRHP eligible (NPS 1995, p. 25):A a religious property deriving primary significance from architectural or artistic distinction or historical importance;B a building or structure removed from its original location, but which is significant primarily for architectural value, or which is the surviving structure most importantly associated with a historic person or event;C a birthplace or grave of a historical figure of outstanding importance if there is no appropriate site or building directly associated with his or her productive life;D a cemetery which derives its primary significance from graves of persons of transcendent importance, from age, from distinctive design features, from association with historic events; E a reconstructed building when accurately executed in a suitable environment and presented in a dignified manner as part of a restoration master plan, and when no other building or structure with the same association has survived;F a property primarily commemorative in intent if design, age, tradition, or symbolic value has invested it with its own exceptional significance; orG a property achieving significance within the past 50 years if it is of exceptional importance.Once the significance of a resource has been determined, the resource then must be assessed for integrity. Integrity is 1) the ability of a property to illustrate history and 2) possession of the physical features necessary to convey the aspect of history with which it is associated (NPS 1995, p. 44). The evaluation of integrity is grounded in an undproperties either retain integrity (that is, convey their significance) or they do not. To retain integrity, a property will always possess several, and usually most, of the seven aspects of integrity (NPS 1995, pp. 4445):1.Locationis the place where the historic property was constructed or the place where the historic event occurred.2.Designis the combination of elements that create the form, plan, space, structure, and style of a property.3.Settingis the physical environment of a historic property.4.Materialsare the physical elements that were combined or deposited during a particular period and in a particular pattern or configuration to form a historic property.5.Workmanshipis the physical evidence of crafts of a particular culture or people during any given period in history or prehistory.6.Feeling7.Associationis the direct link between an important historic event or person and a historic property.1.4.2 StateCaliforniaRegisterofHistoricalResourcesplace, record, or manuscript which is historically or archaeologically significant, or is significant in the architectural, Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 20224
(California Public Resources Code Section 5020.1[j]indicate what properties are to be protected, to the extent prudent and fe(California Public Resources Code Section 5024.1[a]). The criteria for listing resources on the CRHR were expressly developed to be in accordance with previously established criteria developed for listing in the NRHP, enumerated below. According to California Public Resources Code Section 5024.1(c) (14), a resource is considered historically 1.history and cultural heritage.2. Is associated with the lives of persons important in our past.3. Embodies the distinctive characteristics of a type, period, region, or method of construction, or represents the work of an important creative individual, or possesses high artistic values.4. Has yielded, or may be likely to yield, information important in prehistory or history.In order to understand the historic importance of a resource, sufficient time must have passed to obtain a scholarly perspective on the events or individuals associated with the resource. A resource less than 50 years old may be considered for listing in the CRHR if it can be demonstrated that sufficient time has passed to understand its historical importance (see 14 CCR 4852[d][2]).The CRHR protects cultural resources by requiring evaluations of the significance of prehistoric and historic resources. The criteria for the CRHR are identical to those for the NRHP, and properties listed or formally designated as eligible for listing in the NRHP are automatically listed in the CRHR, as are the state landmarks and points of interest. The CRHR also includes properties designated under local ordinances or identified through local historical resource surveys.CaliforniaEnvironmentalQualityActAs described further below, the following CEQA statutes and CEQA Guidelines are of relevance to the analysis of archaeological, historical, and tribal cultural resources:1.2. California Public Resources Code Section 21084.1 and CEQA Guidelines Section 15064.5(a) define adverse change in the significance of an historical resouproject would materially impair the significance of an historical resource.3.4. California Public Resources Code Section 5097.98 and CEQA Guidelines Section 15064.5(e) set forth standards and steps to be employed following the accidental discovery of human remains in any location other than a dedicated ceremony.5. California Public Resources Code Sections 21083.2(b)-(c) and CEQA Guidelines Section 15126.4 provide information regarding the mitigation framework for archaeological and historic resources, including examples of preservation-in-place mitigation measures; preservation-in-place is the preferred manner of mitigating impacts to significant archaeological sites because it maintains the relationship between Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 20225
artifacts and the archaeological context and may also help avoid conflict with religious or cultural values of groups associated with the archaeological site(s).Guidelines Section 15064.5[b]as significant in a historical resources survey (meeting the requirements of California Public Resources Code Section 5024.1[q]). clearly demonstrated that, without merely adding to the current body of knowledge, there is a high probability that it meets any of the following criteria:1. Contains information needed to answer important scientific research questions and that there is a demonstrable public interest in that information.2. Has a special and particular quality such as being the oldest of its type or the best available example of its type.3. Is directly associated with a scientifically recognized important prehistoric or historic event or person.All historical resources and unique archaeological resources as defined by statute are presumed to be historically or culturally significant for purposes of CEQA (California Public Resources Code Section 21084.1; CEQA Guidelines Section 15064.5[a]). The lead agency is not precluded from determining that a resource is a historical resource even if it does not fall within this presumption (California Public Resources Code Section 21084.1; CEQA Guidelines Section 15064.5[a](California Public Resources Code Section 21083.2[a]; CEQA Guidelines Section 15064.5[c][4]).relocation, or alteration of the resource or its immediate surroundings such that the significance of an historical [b][1]; California Public Resources Code Section 5020.1[q]). In turn, the significance of a historical resource is materially impaired when a project:1. Demolishes or materially alters in an adverse manner those physical characteristics of an historical resource that convey its historical significance and that justify its inclusion in, or eligibility for, inclusion in the California Register; or2. Demolishes or materially alters in an adverse manner those physical characteristics that account for its inclusion in a local register of historical resources pursuant to section 5020.1(k) of the Public Resources Code or its identification in an historical resources survey meeting the requirements of section 5024.1(g) of the Public Resources Code, unless the public agency reviewing the effects of the project establishes by a preponderance of evidence that the resource is not historically or culturally significant; or3. Demolishes or materially alters in an adverse manner those physical characteristics of a historical resource that convey its historical significance and that justify its eligibility for inclusion in the California Register as determined by a lead agency for purposes of CEQA.

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1.4.3 LocalThe City of Thousand Oaks has local designation criteria for both landmarks and points of historical interest, as outlined below:Sec.1-9.203.Definitions.(a) Landmark. For purposes of this article, site, area, place, or natural formation which has historic, architectural, archaeological, cultural or aesthetic significance to the City of Thousand Oaks, and:(1)architectural or natural history;(2) Is associated with events that have made a significant contribution to the broad (3) Is associated with the lives of persons important to the City;(4) Has yielded or has the potential to yield information important to the prehistory or history of the City; or,(5) Embodies the distinctive characteristics of a type, period, region, or method of construction, represents the work of a master, or possesses high artistic values.(b)object, building, structure, site, area, place, or natural formation which has historic, architectural, archaeological, cultural or aesthetic significance to the City of Thousand Oaks that:(1) No longer exists or was associated with historic events, important persons or embodied a distinctive character or architectural style;(2) Has been altered to the extent that the integrity of the original workmanship, materials or type has been substantially compromised; or,(3) Is a site of an historic event which has no distinguishable characteristics other than that an historic event occurred there and the site is not of sufficient historic significance to justify the establishment of a landmark.(§ 1, Ord. 868-NS, eff. September 18, 1984, as amended by § 1, Ord. 1015-NS, eff. December 6, 1988, Ord. 1276-NS, eff. February 12, 1997, and § 1, Ord. 1420-NS, eff. December 17, 2003)The City of Thousand Oaks General Plan Conservation Element Update (Chapter Eight, Section M) also outlines cityspecific policies and implementation measures and how they pertain to cultural resources (City of Thousand Oaks 2013, p. 47). M.CulturalResourcesPoliciesCO33 All information or maps on file with the City pertaining to the location of previously recorded archaeological sites within the Thousand Oaks Planning Area shall remain confidential unless specifically authorized to be released to the public by local Native American organizations.

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CO34Management of cultural resources such as archaeological sites, historic structures or places shall emphasize resource protection and preservation. CO35 The preferred method for protecting any previously recorded archeological site shall be by deed restriction as permanent "open space", in order to prevent any future development or use that might otherwise adversely impact these resources. CO36 Decisions pertaining to the disposition of archaeological, historical and cultural resources shall be made in concert with recognized public agencies, groups or individuals having jurisdiction, expertise or interest in these matters, including but not limited to the State Office of Historic Preservation, Thousand Oaks Cultural Heritage Board and local Native American organizations, including other designated representatives and affected property owners. ImplementationMeasuresContinue to conduct archaeological field surveys as deemed to be necessary, while utilizing comprehensive resource management procedures to test, salvage, stabilize and store locally excavated artifacts.Support the efforts of local citizens, appointed committees or other designated public agencies and private institutions that are working to conserve archaeological and historic resources. Full public discussion is encouraged prior to any action being taken.1.5 Built Environment Study AreaThe Built Environment Study Area is shown on Figure 2, which contains Map ID numbers assigned to all buildings and structures at the Hill Canyon Treatment Plant. Delineation of the Built Environment Study Area took into consideration the extent of Project construction and implementation that may lead to impacts to historical resources.Current professional practice commonly groups activities that could cause a substantial adverse change to historical resources into direct and indirect impact considerations. Direct impact considerations are commonly linked to physical Project construction activities including but not limited to demolition, construction-related ground borne vibration, and property takes. Impact considerations commonly considered indirect are related to potential post-construction effects of a project that is near a historical resource, such as noise, shadow, or visual effects, depending on the circumstances.As detailed in the Project description, the boundary of the Project site includes the entirety of the 60-acre Hill Canyon Treatment Plant which was initially constructed in 1961 and is located at 9600 Santa Rosa Road (APNs 552-0-130-015, 520-0-300-115, and 667-0-120-170). The proposed Project is limited to the construction of additional storm drain pipes, a debris basin and a channel, located near the confluence of the north and south forks of Arroyo Conejo Creek. No previously recorded or evaluated built environment properties or previously identified national, state, or local historic districts, were identified within or immediately adjacent to the Project site. there are no buildings or structures over the age of 45 years located directly adjacent to the Project site. As such, the Built Environment Study Area is limited to the extent of the Project boundary. The Hill Canyon Treatment Plant, a multi-component facility containing buildings and structures over the age of 50, is the only built environment property in the Built Environment Study Area requiring evaluation and consideration under CEQA. Components of Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 20228
the treatment plant and their corresponding built year are listed below in Table 1 and illustrated in Figure 2. For organizational purposes, buildings and structures are numbered with map identification (Map ID) numbers north to south within the Project site/facility boundary.Table 1. Property Located in Built Environment Study Area - Hill Canyon Treatment Plant Buildings and StructuresMapIDNoBuilding/StructureName(YearBuilt)1 Operations Building (c. 1998)2 Thickening Building (1983) 3 Biogas Tanks (2005)4 Digester No.1 (1970)Digestor No. 2 (1961) Digestor No. 3 (c. 1998)5 North Headworks (1961) 6 Primary Clarifier No. 1, and 4 (1961), Primary Clarifier No. 2 (c. 1966), andPrimary Clarifier No. 3 (1970) 7 Maintenance Storage Building (2003)8 Cart Garage and Shop Building (1961)9 Aeration System No. 1 (1961)Aeration System No. 2 (1970)10 Blower Building No. 1 (2003) 11 Primary Effluent Splitter Box (2003)12 Secondary Clarifier No. 1 (1970) Secondary Clarifier No. 2 (1987)Secondary Clarifier No. 3 (c. 1998)13 Vehicle Fueling Station (2003)14 Wastewater Pump Station: North building (2003) South structure (c. 2007)15 Blower Building No. 2 (2003)16 Chlorine Contact Channel (1970) 17 Filter Backwash Pump Station (1987)18 Bio-Reactor Basins No. 3, 4, 5, and 6 (2003)19 South Headworks (1987)20 Filter Influent Pump Station No. 1 (2005)Filter Influent Pup Station No. 2 (c. 1998)21 Tertiary Filters and Filter Expansions (c. 1979)22 Chemical Building (c. 1979)23 Maintenance Building No. 1 (c. 1979) 24Maintenance Building No. 2 (c. 1998) 25 Flow Equalization Basin No. 1 and 2 (c. 1998)26 Michael Lamber Drying Beds (1977)27 Dewatering/Generator Building (c. 1998)28 Sodium Bisuphite Storage Structure (2003) Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 20229
Table 1. Property Located in Built Environment Study Area - Hill Canyon Treatment Plant Buildings and StructuresMapIDNoBuilding/StructureName(YearBuilt)29 Mixed Liquor Channel (c. 1992)30 Wastewater Reclamation System (c. 1979) Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202210

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2 Methodsto the records search and relevant built environment results, archival and property-specific research, and the field survey summary.2.1 Records Search ResultsOn March 24, 2022, staff at the South Central Coast Information Center (SCCIC), located on the campus of California State University, Fullerton, provided the results of a California Historical Records Information Systemrecords search for the Project site and a 0.5-mile radius. Due to COVID-19, the SCCIC notified researchers that they are only able to provide data for Ventura County that has already been digitized. As such, not all available data known to California Historical Records Information System may be provided in the records search. The California Historical Records Information System records search results provided by the SCCIC included their digitized collections of mapped prehistoric and historic archaeological resources and historic built-environment resources; Department of Parks and Recreation site records; technical reports; archival resources; and ethnographic references. The confidential records search results are also provided in the Confidential Appendix.PreviouslyRecordedCulturalResourcesThe SCCIC records indicates that eight cultural resources have been previously recorded within 0.5 miles of the Project site, none of which overlap or are adjacent to the Project site. Seven resources are prehistoric archaeological sites and one is a historic archaeological site. No previously recorded built environment properties were identified in the records search. Table 2, below, summarizes all previously recorded cultural resources, including archaeological resources identified within the search area, preceded by a brief summary of each prehistoric site. Table 2. Previously Recorded Cultural Resources within a 0.5-Mile Radius of the Project SiteSCCICIDTrinomialDescriptionRecordingEventsNRHPStatusProximitytoProjectSiteP-56-000170CA-VEN-000170Prehistoric Site: Lithic scatter1967 (King) 7R: Identified in Reconnaissance Level Survey: Not evaluated440 meters, 1444 feet (south)P-56-000171CA-VEN-000171Prehistoric Site: Lithic scatter; ground stone1967 (C. King); 1981 (Brian D. Dillon); 1989 (Richard Angula and Kenneth Becker)7R: Identified in Reconnaissance Level Survey: Not evaluated544 meters, 1785 feet (south)P-56-000172CA-VEN-000172Prehistoric Site: Lithic scatter1967 (C. King); 1989 (Richard Angula and Kenneth Becker)7R: Identified in Reconnaissance Level Survey: Not evaluated596 meters, 1955 feet (south)P-56-000173CA-VEN-000173Prehistoric Site: Lithic scatter; ground stone1967 (King) 7R: Identified in Reconnaissance Level Survey: Not evaluated751 meters, 2464 feet (south)P-56-000445CA-VEN-000445Prehistoric Site: Lithic scatter1977 (Santa Cruz, Ivie)7R: Identified in Reconnaissance Level Survey: Not evaluated415 meters, 1362 feet (southwest) Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202212
Table 2. Previously Recorded Cultural Resources within a 0.5-Mile Radius of the Project SiteSCCICIDTrinomialDescriptionRecordingEventsNRHPStatusProximitytoProjectSiteP-56-000446CA-VEN-000446Prehistoric Site: Small lithic scatter1977 (Whitley and Ivie)7R: Identified in Reconnaissance Level Survey: Not evaluated622 meters, 2041 feet (northwest)P-56-001602Prehistoric Site: Marine shell scatter, fire affected rock and projectile point2000 (M. Maki)7R: Identified in Reconnaissance Level Survey: Not evaluated26 meters, 85 feet (southwest)P-56-100078Historic Site: Steel plate storage tank1997 (W. Bonner); 2001 (D. Whitley)7R: Identified in Reconnaissance Level Survey: Not evaluated259 meters, 850 feet (west)PreviouslyConductedCulturalResourceStudiesResults of the cultural resources records search indicate that 19 previous cultural resource studies have been conducted within 0.5 miles of the Project site between 1975 and 2006. Of these studies, five overlap the Project site; VN-84, -101, --1527, -1573, and -1593. Table 3, below, details all 19 previous cultural resources studies preceded by a brief summary of the available reports overlapping the Project site.Report No. VN-84Archaeological Resource Survey and Preliminary Impact Assessment of the MGM Ranch Property Thousand Oaks, California (Clewlow 1977), documents the results of an archaeological survey and impact assessment consisting of archival record search, literature review and pedestrian survey. The area of study overlaps the southwest area of the Project site, as well as the southernmost extent of the larger, primary section. The report relocated and re-evaluated five previously recorded sites and identified 21 new archaeological sites. None of the sites overlap the Project site. A variety of mitigation measures were recommended, including testing, capping and the creation of open space to preserve the cultural resources noted. It was further recommended that a General Research Design be created for the area, to carry out any mitigation efforts within the framework of a comprehensive research design.Report No. VN-101Conejo Canyons Study(Rosen 1976), documents the results of a study to address existing environmental resources of the Conejo Canyons and to suggest planning policy, criteria and standards for the future use of and conservation of those resources. The area of study overlaps all areas of the Project site. The goal of the survey was to record existing resources; the archaeology component was archival research and recounting of known resources. The records search indicated there were 26 to 32 known sites recorded, of which 21 were either disturbed or destroyed. The large number of known sites led the study to indicate the area has a high degree of archaeological sensitivity.Report No. VN-1527An Historic Study of the Property Known As the M.G.M Ranch a Planned Community by Shapell Industries Inc.(Allen 1978), documents the results of a historic study of M.G.M. Ranch property as part of a greater study for a planned Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202213
development. The area of study overlaps the southwest area of the Project site, as well as the southernmost extent of the larger, primary section. The primary focus of the report, formally recorded by Patricia Allen, is the historic record of the M.G.M. property as documented through grants and purchases. Included in the appendix are records of three archaeological resource surveys, although the reports are not attached. The reports indicated that there were 24 known archaeological sites within the boundaries of the Specific Plan and mitigation recommendations about avoidance, excavation, and cultural monitoring were included.Report No. VN-1573Phase 1 Archaeological Survey and Impact Assessment of Approximately 4 Linear Miles for the Unit W & F Interceptor Replacement Project Arroyo Conejo Thousand Oaks, Ventura County, California (Maki 1997), documents the results of a Phase I cultural resources investigation in the Arroyo Conejo and selected tributary canyons, consisting of archival record research, literature review, consultation with local Native Americans and pedestrian survey. The area of study overlaps the southwestern area of the Project site. The study referenced multiple archaeological sites located on the bluffs and hills above the Arroyo Conejo, but none within the Pe I construction zone. Mitigation recommendations included archaeological monitoring and a temporary work halt order should archaeological resources or human remains be unearthed.Report No. VN-1593Cultural Resources Assessment of the Hill Canyon Regional Recreational Facility, Thousand Oaks, Ca(Bonner 1997), documents the results of a Phase I cultural resources assessment of the Acacia Hill Canyon Regional Recreational Facility, consisting of archival records research, literature review, and pedestrian survey of the subject property. The area of study overlaps the southwest area of Project site and is adjacent to the larger, primary section. Mitigation recommendations included archaeological monitoring during any construction activity, including vegetation clearance near known prehistoric sites. The author further recommended subsurface testing should any buried midden component be encountered.Table 3. Previous Technical Studies Within a 0.5-Mile Radius of the Project SiteSCCICReportNo.(VN-)AuthorsDateTitleAddressesProjectSite00033Maxwell, Thomas J.1975Environmental Impact Report Sch. No. 75051421 Unit "y" Sewer Replacement I.D. No. 76-1258, F.Y. 1975-76No00059 Rosen, Martin D. 1977 Evaluation of the Archaeological Resources and Potential Impact of Proposed Development of 632 Acres in Thousand Oaks, CaliforniaNo00084Clewlow, William C. Jr.1977An Archaeological Resource Survey and Preliminary Impact Assessment of the MGM Ranch Property Thousand Oaks, CaliforniaYes00101 Rosen, Martin D. 1976 Conejo Canyons Study Yes00103 Clewlow, William C. Jr.1978 Preliminary Archaeological Investigations on MGM Ranch: 4-VEN-170, 4-VEN-171, 4-VEN-272, 4-VEN-437, 4-VEN-449No Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202214
Table 3. Previous Technical Studies Within a 0.5-Mile Radius of the Project SiteSCCICReportNo.(VN-)AuthorsDateTitleAddressesProjectSite00231 Lopez, Robert 1980A Re-evaluation of the Archaeological Resources Contained Within and Directly or Indirectly Impacted by the 633 Acres Proposed for Tract 3465 Thousand Oaks, Ventura County, CaliforniaNo00403 Dillon, Brian D. 1977 CA-VEN-171: Boundary Test Report No00914 Whitley, David S. 1985 Archaeological Survey of Portions of the Northrop Corporation Property, Newbury Park, Ventura County, CaliforniaNo01087Clewlow, William C. Jr.1991Letter Report on Preliminary Archaeological Mitigative Procedures at Site CA-VEN-170No01088Clewlow, Theresa A. and C.W. Clewlow1991Archaeological Investigations at CA-VEN-445 City of Thousand Oaks, CaliforniaNo01130Drover, Christopher E.1988Environmental Impact Evaluation: AnArchaeological Assessment of Vesting Tentative Tract Map 4366--Rancho Conejo City of Thousand Oaks, CaliforniaNo01419 Maxwell, Thomas J.1976 Unit "Y" Sewer Replacement Sch. No. 75051421 City of Thousand OaksNo01527 Allen, Patricia A. 1978 An Historic Study of the Property Known As the M.G.M Ranch a Planned Community by Shapell Industries Inc.Yes01573 Maki, Mary K. 1997Phase 1 Archaeological Survey and Impact Assessment of Approximately 4 Linear Miles for the Unit W & F Interceptor Replacement Project Arroyo Conejo Thousand Oaks, Ventura County, CaliforniaYes01593 Bonner, Wayne 1997Cultural Resources Assessment of the Hill Canyon Regional Recreational Facility, Thousand Oaks, Ca.Yes01864 Maki, Mary K. 2000 Cultural Resource Monitoring Results for the Dewatering and Generator Building at the Hill Canyon Wastewater Treatment PlantNo01866 Romani, John F. 2000Results of Archaeological Phase II/phase III Excavations Damage Assessment and Repatriation of Disinterred Native American Remains in Accordance With the Requirements of NAGPRA at CA-VEN-1602 Hill Canyon Waste Water Treatment PlantNo02505 Maki, Mary K. 2006Phase 1 Cultural Resources Investigation of Approximately 0.8 Ac for the Mesa Feeder Crossing Relocation Project Arroyo Conejo, Thousand Oaks, Ventura Co.No Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202215
Table 3. Previous Technical Studies Within a 0.5-Mile Radius of the Project SiteSCCICReportNo.(VN-)AuthorsDateTitleAddressesProjectSite02637 Whitley, David S. 2002Extended Phase I Archaeological Survey for the Hill Canyon Wetlands Mitigation Study Area, Thousand Oaks, Ventura County, CaliforniaNo2.2 Building Development and ArchivalBackground ResearchIn addition to the records search results from SCCIC, repositories, historical records, and related additional reportswere accessed. These additional sources are summarized below. HillCanyonTreatmentPlantRecordDrawingsIn March 2022, City of Thousand Oaks shared four sets of record drawings with Dudek, detailing plant expansions and renovation projects in 1986, 1987, 2003, and 2005. These plan sets were used as source materials in Section 3, Historical Context, and Section 4, Results of Identification and Evaluation Efforts, of this report.The following record drawings were shared:Hill Canyon Wastewater Treatment Plant Equalization Basin Lining Project (James M. Montgomery Consulting Engineers Inc. 1986)Hill Canyon Wastewater Treatment Phase 1B Expansion. (James M. Montgomery Consulting Engineers Inc. 1987)Hill Canyon Wastewater Treatment Plant Expansion/Upgrade Phase II. (CH2M Hill 2003)Hill Canyon Wastewater Treatment Plant Expansion and Upgrade Phase III. (CH2M Hill 2005)CityofThousandOaksPublicRecordsRequestOn April 11, and again on April 26, 2022, Dudek submitted a public records request for the original 1961 as-built drawings and information related to the establishment and purchase of the Hill Canyon Treatment Plant by City of Thousand Oaks. On May 10, 2022, Dudek received a response from Carolyn Valdez, a Records Management Specialist at the Community Development Department. Ms. Valdez gave Dudek staff a permit report showing all permits and inspections of the Hill Canyon Treatment Plant after it became the property of the City in 1966. Earlier permits were not available and Ms. Valdez recommended reaching out to the County of Ventura Resource Management Agency Building and Safety Department to see if they held the original as-builts and records. CountyofVenturaResourceManagementAgencyBuildingandSafetyDepartmentAt the suggestion of City of Thousand Oaks, on May 10, 2022, Dudek submitted a public records request for the original 1961 as-built drawings of the Hill Canyon Treatment Plant or records related to its initial development and the Conejo Valley Sanitary Company. To date, no response has been received.

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ThousandOaksLibraryOn March 23, 2022, Dudek visited and reviewed the local history collections at the Thousand Oaks Library, including photographs, newspapers articles, books, journals, and archival collections summaries related to the general history and establishment of Thousand Oaks and the Hill Canyon Treatment Plant. These items were used as source materials in Section 3 and Section 4 of this report. HistoricalNewspapersDudek accessed historical editions of local newspapers while researching for Section 3 and Section 4 of this report. These local newspapers includeVentura County Star, Ventura County Star-Free Press, theBakersfield Californian, theLos Angeles Evening Citizen News,the Los Angeles Times, Santa Cruz Sentinel, andSacramento Bee.HistoricalAerialPhotographsA review of historical aerial photographs was conducted as part of the archival research effort from the following years: 1959, 1965, 1970, 1978, 1980, 1985, 1989, 2002, 2005, 2009, 2016, and 2018. Historic aerials were used to obtain approximate dates of construction and dates of alterations for buildings and structures within the Built Environment Study Area. These construction dates and changes to the subject property, as well as the surrounding area, are noted below in Table 4. Circa dates for construction of buildings and structures were chosen by selecting the median year between two aerials photographs dates, whenever aerial photographs were used to estimate the construction (NETR 2022; UCSB 2022). Table 4. Aerial PhotographsYearDescription1959 The Subject area was an undeveloped, crescent-shaped valley located in the Simi Hills. 1961 In 1961, Hill Canyon Treatment Plant appears under construction. Clearly visible are the original Administration Building; Map ID No. 4: Digester No. 2; Map ID No. 6: Primary Clarifiers No. 1 and No. 4.; and Map ID No. 8: the Cart Garage and Shop Building. 1965By 1965, construction of the complex appearedcomplete, and additional buildings were visible including Map ID No. 6: Primary Clarifiers 1, 2, and 4; and Map ID No. 9: Aeration System No. 1. Map ID No. 4: Digestor No. 2 is located directly west side of the North Fork of Arroyo Conejo while the other original components are clustered west of the river. Two large evaporation ponds were also visible directly south of Map ID No. 9: Aeration System No. 1. 1967Between 1965 and 1967 aerial photographs, Map ID No. 6: Primary Clarifier No. 2 appearsto have been constructed, north of Primary Clarifier No. 41970 No changes to the subject property or the surrounding area were noted.1977By 1977, buildings constructed on the campus included Map ID No. 4: Digestor No. 1, Map ID No. 5: North Headworks, Map ID No. 6: Primary Clarifier 3, Map ID No. 9: Aeration Station 2, Map ID No. 12: Secondary Clarifier No. 1, Map ID No. 16: Chlorine Contact Channel, and Map ID No. 26: the Michael Lambert Drying Beds. Three non-extant ancillary buildings are also present on the property in 1977 aerial. 1978 No changes to the subject property or the surrounding area were noted.1980 Map ID No. 8: Cart Garage and Shop Building receives and addition; Map ID No. 21: Tertiary Filters and Filter Expansions, Map ID No. 22: Chemical Building, Map ID No.23: Maintenance Building No. 1, Map ID No. 30: Wastewater Reclamation System (c. 1979), were in place by 1980.1985 No changes to the subject property or the surrounding area were noted.

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Table 4. Aerial PhotographsYearDescription1989Map ID No. 2: Thickening Building, Map ID No. 19: South Headworks, Map ID No. 12: Secondary Clarifiers No. 1, Map ID No. 17: Filter Backwash Pump Station were in place by 1989.1994Map ID No.29: Mixed Liquor Channelwere in place by 1994. 2002Map ID No.1: OperationsBuilding, Map ID No.4: Digestor No. 3, Map ID No.12:Secondary Clarifiers No. 3, Map ID No. 20: Filter Influent Pump Station No. 2 Map ID No.24: Maintenance Building No. 2, and Map ID No. 27: Dewatering/Generator Building were in place by 2002.2005 Map ID No. 7: Maintenance Storage Building, Map ID No. 10: Blower Building No. 1, Map ID No. 11: Primary Effluent Splitter Box, Map ID No. 13: Vehicle Fueling Station, Map ID No. 15: Blower Building No. 2, Map ID No. 14: Wastewater Pump Station, Map ID No. 18: Bio-Reactor Basin No. 3, 4, 5, and 6, Map ID No. 29: Dewatering/Generator Building, and Map ID No. 14: Wastewater Pump, and Map ID No. 28: Sodium Bisuphite Storage Building Station were in place by 2005. 2009 Map ID No. 14: Wastewater Pump Station was expanded by 2009. Map ID No. 3: Biogas Tanks and Map ID No. 20: Filter Influent Pump Station No. 12016 No changes to the subject property or the surrounding area were noted.2018 No changes to the subject property or the surrounding area were noted.Source:NETR 2022; UCSB 2022.2.3 Built Environment Field MethodsDudek Architectural Historian Kate Kaiser, MSHP, conducted an intensive level survey of the Hill Canyon Treatment plant on March 23, 2022. The survey entailed walking the entire property and documenting the exterior conditions of all buildings proposed for demolition as part of the Project. Each building was documented with notes and photographs, specifically noting character-defining features, spatial relationships, and observed alterations and examining any historic landscape features on the campus. Dudek documented the fieldwork using field notes, digital photography, close-scale field maps, and aerial photographs. Photographs of the campus were taken with a digital camera. All field notes, photographs, and records related to the current study are on filePasadena, California, office.

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3 Historical Context3.1 Early Settlement of Conejo Valley and City of Thousand OaksSpanish, Russian, and British frontiersmen had intermittently explored California between 1529 and 1769 but did not travel into the Conejo Valley until the late eighteenth century. In 1782, Spanish missionaries established Mission San Buenaventura, one settlement in a network of Catholic missions, in the Conejo Valley. In 1803, the Spanish Crown bestowed thousands of acres, later to be organized as Rancho El Conejo , to two retired soldiers: Ignacio Rodriguez and José Polanco (Bidwell 1989, p. 13). In 1821, after more than a decade of intermittent rebellion and warfare, Mexico declared independence from Spain and endeavored to occupy the remote Northern Californian territory by expanding the Spanish land grant system (Starr 2007, p. 107). Although Polanco opted to settle El Pueblo de Nuestra Señora la Reina de los Ángeles de Porciúncula (Los Angeles), Rodriguez and his family relocated to Rancho El Conejo and raised cattle. When Rodriguez died in 1839, he bequeathed his land to his heirs. In 1822, José de la Guerra y predominant rancher in the region (Bidwell 1989, p. 19). De la Guerra y Noriega expanded his holdings to include more than a half-million acres, reaching from the extant Los Angeles County line to the San Luis Obispo, and including land in Sacramento and Marin counties. In Ventura County, land holdings included Rancho El Conejo, measuring 48,178 acres; Rancho Las Posas, totaling 26,623 acres; Rancho Simi, at 113,009 acres; and Rancho Santa Paula y Saticoy, measuring 17,773 acres. De la Guerra y Noriega never lived on Rancho El Conejo, choosing to live and tallow, and hides on Rancho El Conejo (Bidwell 1989, p. 20). De la Guerra y Noriega maintained Rancho El Conejo and his other properties, developed with small, sparse ranching settlements, through the Mexican-era and, after the Treaty of Guadalupe Hidalgo was signed in 1848, into the American-period. Weeks after the United States acquired California, James W. Marshall discovered gold in Coloma, California, catalyzing an influx of gold seekers to flood the rural counties of California. The American emigration into under-developed rancho lands incited litigation between rancho owners, the United States government, and American squatters. Although the Treaty of Guadalupe Hidalgo secured Mexican landowners their full claims, the property owners were required to provide English-language legal documentation and confirm its authenticity to a United States government interested in opening the land to its non-Mexican citizens. The prohibitive cost of lengthy court battles, language barrier, and statewide droughts in the 1850s and 1860s, forced many rancheros to forfeit sections or the entirety of their landholdings between 1848 and the 1870s (Hoover et al. 2002, p. 301). As de la Guerra y Noriega scrambled to legitimize his holdings to the United States government and ward off interlopers and squatters his four ranchos were devastated by prolonged periods of drought, broken by intermittent storms and flash floods. In 1872, de la Guerra y Noriega acres to John Edwards and Howard W. Mills, two Santa Barbara residents. Despite the full sale, Edwards and Mills legally acquired a mere 5,000 acres, with the rest sold was settledand legal titles were formalized, Edwards retained the land where present-day Newbury Park and the northern portion ofThousand Oaks was developed. Mills retained the land where present-day Westlake Village and Hidden Valley are located(Bidwell 1989, p. 23).

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When de la Guerra y Noriega was forced to sell Rancho El Conejo in 1873, both John Edwards and H.W. Mills, by this time established entrepreneurs, seized the opportunity to own land in the agriculturally viable Conejo Valley. The Edwards family maintained a primary residence in Santa Barbara but hired an on-site supervisor to manage their ranch and only visited occasionally. Mills constructed his primary residence near where the Westlake Village neighborhood is located today. A third emigrant, Egbert Starr Newbury, a health seeker from Minnesota, purchased 2,259 acres in 1873, near present-daybefore purchasing a second, 3,285-acre parcel in the western end of the valley. Arriving emigrants purchased land and and developed wheat farms, which covered 15,000 acres of the valley by 1875 (Bidwell 1989, p. 23). As Euro-Athe coastal city markets and for mail services. In 1876, Conejo Valley gained a Post Office, the Ventura Free Press, the Grand Union Hotel, churches, a one-room school, and commercial businesses (Bidwell 1989, p. 23-26). Irrigation, however, was still not existent in the valley. Farmers who were experimenting with walnut and acycle to produce their crops (Bidwell 1989, p. 23). Cattle ranching, which had become expensive to maintain after the drought-flood disasters of the 1860s, was replaced with grazing vast flocks of sheep (Bidwell 1989, p. 24). As the nineteenth century drew to a close, the agricultural community continued to grow when the first major regional roads, two-track wagon roads constructed by local farmers, linked the Conejo Valley to the ports at Hueneme and Los Angeles. The roads were funded by community citizens after Ventura County agreed to contribute sixty dollars and reduced travel time to regional ports from a multi-day journey to just over twenty-four hours (Bidwell 1989, p. 31). In 1887, the Ventura County Railroad opened, linking Oxnard to Port Hueneme but because of the distance between the transportation network and Conejo Valley, farmers began to send their produce to Simi Valley where Branch rail station loaded both freight and passengers (Bidwell 1989, p. 31; NETR 2022). At the turn of the twentieth -American settlers had sold or bequeathed their land to the next generation of landowners. In 1902, Conejo Pass Road was constructed with 3,000 dollars from Ventura County, and the rest was obtained through private fundraising (Bidwell 1989, p. 32). In 1910, Harold and Doctor Edwin Janss purchased 10,000 acres of prime agricultural land from the heirs of John Edwards and developed a ranch for thoroughbred racehorses (Bidwell 1989, 34-35). The Janss brothers organized the Janss Investment Corporation (Janss Corp.) and entered the greater-Los Angelesreal estate market. Janss Corp. developed the novel practice of chauffeuring clients to view purchasable lots in the Conejo, San Fernando, and Imperial Valleys, as well as in Delano, Yorba Linda, Boyle Heights, the City of Monterey, and Los Angeles. On their private ranch, the Janss brothers raised cattle and horses while cultivating beans and grains. Today, their homestead is the site of The Oaksshopping center in downtown Thousand Oaks (Bidwell 1989, p. 35-36; City of Thousand Oaks 2022). Off of their private homestead, planned aand subdivided residential lots. As corporations, small real estate companies, and private speculators invested in local development in the 1920s, a second (City of Thousand Oaks 2022). In 1922, several real estate companies and private developers purchased large parcels in Conejo Valley, subdivided the land, and sold lots to individual buyers. To name the town, the Conejo Valley School District held a contest and awarded five dollars and a small parcel to 14-year-sold for 10street consisted of a residence that housed the Post Office, a small grocery store, a restaurant, and a small library (Bidwell 1989, p. 37; City of Thousand Oaks 2022). In 1927, Louis Goebel opened the Lion Farm in the planned, idyllic community Jungleland, Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202221
attracted throngs of visitors that settled in the town, and contributed to the local economy before returning home, or Birth of a Nation, Tarzan, and The Adventures of Robin Hoodwere filmed at the farm and in Thousand Oaks (City of Thousand Oaks 2022).businesspeople, entrepreneurs, and families purchased properties in the picturesque rural community. Prominent businesspeople, including newspaper magnate William Randolph Hearst and founder of the Albertson Company grocery chain B.B. Albertson, purchasedthousands of acres in Conejo Valley between the late 1920s and early 1930s. In the 1940s, another wave of Hollywood natural beauty, towering hills, and large ranching properties. In 1956, the Talley Corporation acquired land from Albertson first business complex (Bidwell 1989, p. 42). In the latter half of the twentieth century, large technology firms, including Packard-Bell Electronics, Westinghouse Astroelectronics Laboratory, and the Semtech Corporation drew new residents, educational programs and universities, and businesses to the valley. Over time, the Rancho El Conejo Industrial Park expanded as new companies relocated to the fast-growing commercial hub of Conejo Valley Industrial Park and, in the twentieth and twenty-first centuries, has employed thousands of Conejo Valley and Thousand Oaks residents (Bidwell 1989, p. 44).Janss Corp. drove the early development of Thousand Oaks and Conejo Valley. In 1956, Janss Corp. hired Southern a ten-year master development plan for homes, schools, parks, commercial areas, and non-polluting industries in Thousand Oaks. Within five years, the town grew from 1,500 residents to 12,000 residents. Janss Corp., continued to develop neighborhoods surrounding Thousand Oaks through the 1960s, transforming the once-small rural community into a contemporary suburban city (Bidwell 1989, p. 43). By the mid-1960s, the area grew to hold commercial and industrial businesses, lodgings, recreational activities, churches, libraries, and public education facilities (Bidwell 1989, p. 43-45).Construction and growth continued to be the priority for Thousand Oaks in the mid-1960s as hundreds of houses and residential communities were constructed every month, requiring the support of a wastewater treatment plant. During this period of intensive growth, sanitation and water supply became a driving force in the developing community. In 1963, the Janss Corp.-owned Village Water Company laid a pipeline that pumped 720,000 gallons of water a day from wells on two Camarillo ranches to Thousand Oaks, which had expanded to over 9,100 acres and was populated with nearly 20,000 residents. Pulling from local wells and springs, however, was not enough to offset demand in the rapidly expanding town and Thousand Oaks also joined the Metropolitan Water District (Bidwell 1989, p. 48). In 1964, the City of Thousand Oaks was incorporated through a popular community vote. The first agenda item was to create the City of Thousand Oaks Water Department, which obtains its supply from the State Water Project and imports water from Lake Oroville in Northern California, the Calleguas Municipal Water District, and the Calleguas Lake Bard Water Filtration Facility and Reservoir. Today, The City of Thousand Oaks boasts a population of 127,648, and remains a bedroom community for the greater Los Angeles and Ventura areas. The City retains its balance between local industries and residential expansion, while also maintaining recreational and natural open spaces (Bidwell 1989, p. 43-45; City of Thousand Oaks 2022; WaterZen 2022).3.2 Subject Property: Hill Canyon Treatment PlantAs the Conejo Valley and Thousand Oaks regions continued to develop in the mid-twentieth century, the need for a centralized wastewater treatment facility was apparent as community growth outpaced the abilities of private septic Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202222
tanks, the most common method of waste disposal in the region. As a result, a private company called the Conejo Valley Sanitary Company was formed, and permits were acquired to build a wastewater plant and sewer connections for the communities of Newbury Park and Thousand Oaks. Pomeroy & Associates, a Pasadena engineering firm specializing in wastewater design and studies, was retained to design the plan. Construction of the facility began in December 1959, and the treatment plant, minimizing the electrical and environmental clean-up costs for Thousand Oaks. Janss Corp. and California Lutheran College donated two million dollars to fund the development of the Hill Canyon Treatment Plant (Los Angeles Times 1962, p. 118; Bidwell 1989, p. 49; Ventura County Star 1961, p. 2).The plant was completed in 1961, and originally included nine buildings and structures: Map ID No. 4: Digestor No. 1, Map ID No. 5: North Headworks, Map ID No. 6: Clarifiers 1, 2, and 4, Map ID No. 8: the Cart Garage and Shop Building, and Map ID No. 9: Aeration Station 1 (Exhibit 1) that are still present at the site. Two large settling ponds and several non-extant buildings were also part of this original phase of construction (Exhibit 2). Initially, the Hill Canyon Treatment Plant was designed to serve up to 90,000 people. After its incorporation in 1964, the City of Thousand Oaks acquired the Hill Canyon Treatment Plant on July 1, 1966, from the Conejo Valley Sanitary Company. Average daily flow design capacity of the plant started around 4 MGD in the late 1960s. The same year, the City hired firm Pomeroy & Associates to add Sludge Dewatering Facilities to the Hill Canyon Plant, just south of the main activity area. This project was completed by 1968. (Bidwell 1989, p. 49; City of Thousand Oaks 1966; City of Thousand Oaks 2022; Gannett-Fleming 2020, p. 1-1; NETR 2022; Pomeroy & Associates 1966, pp.1-7; Ventura County Star 1961, p. 2; UCSB 2022).Exhibit1.Hill Canyon Treatment Plant facilities, the digester (left), the activated sludge unit (center), and the office/laboratory (right), under construction c. 1960.

Source:City of Thousand Oaks Library 2022a.

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Since the initial 1960s construction the City completed multiple expansion projects. In 1970, the Phase I Expansion Project for Hill Canyon Treatment plant was approved by the City Council and Mayor. The Phase I construction wasdeveloped directly south of the original building complex, included Map ID No. 4: Digester No. 3, Map ID No. 5: North Headworks, Map ID No. 6: Primary Clarifier No. 3, Map ID No. 9: Aeration System No. 2, and Map ID No. 12: Secondary Clarifier No. 1. At the time, domestic, commercial, and industrial customers in the City of Thousand Oaks generated an average of eight million gallons of wastewater per day. The City of Thousand Oaks prepared for continued suburban growth, and approved a treatment plant expansion that accounted for the storage and treatment of fourteen million gallons of wastewater per day (City of Thousand Oaks 1970; Bidwell 1989, p. 47; NETR 2022; UCSB 2022). In 1977, another expansion project was approved by the City, called Phase 1B. Phase 1B began in 1977 and consisted of multiple projects which extended to 1987. In 1977, the improvements consisted of expanding the property further south and creating two new sludge drying beds (now a solar field), and preparation for Map ID No. 21: Tertiary Filters Building Map ID No. 22: Chemical Building, Map ID No. 23: Maintenance Building No. 1, and Map ID No. 30: the Wastewater Reclamation System (City of Thousand Oaks 1977; James M. Montgomery Consulting Engineers Inc 1977; NETR 2022; UCSB 2022).

Exhibit2.1967 aerial photograph of the Hill Canyon Treatment Plant taken from the MGM Studio property, view facing south.

Source:City of Thousand Oaks Library 2022b.

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The Phase 1B Expansion Project continued into the 1980s. In 1983, Map ID No. 2: Thickening Building, then called a In 1986 and again in 1987, the plant was expanded again to contain and treat over nine million gallons of sewage and wastewater per day and served 29,000 people. Facilities associated with screening, grit removal, two rounds of removing solid waste, nutrient removal, multimedia filtration, disinfection, and dichlorination were developed. The treated water was discharged into Calleguas Creek, which runs north to south and terminates at the Pacific Ocean at Naval Base Fort Mugu. Solids are buried at the Simi Valley landfill (Bidwell 1989, p. 63; City of Thousand Oaks 2022). By 1987, facilities associated with screening, grit removal, two rounds of removing solid waste, nutrient removal, multimedia filtration, disinfection, and de-chlorination were developed. In 1987, Map ID No. 19: South Headworks, Map ID No. 12: Secondary Clarifiers No. 2, and Map ID No. 17: Filter Backwash Pump Station were constructed (James M. Montgomery Consulting Engineers Inc 1983, 1986, 1987; NETR 2022; UCSB 2022). Between 1989 and 1994 Map ID No. 29: Mixed Liquor Channel was constructed. In between 1994 and 2002 another plant expansion took place and Map ID No. 1: Operations Building, Map ID No. 4: Digestor No. 3, Map ID No. 12: Secondary Clarifiers No. 3, Map ID No. 20: Filter Influent Pump Station No. 2, Map ID No. 24: Maintenance Building No. 2, Map ID No. 27: Dewatering/Generator Building, and Map ID No. 25: Flow Equalization Basin No. 1 and 2 were built (NETR 2022; UCSB 2022).In 2003, the plant was expanded again, and Map ID No. 7: Maintenance Storage Building, Map ID No. 10: Blower Building No. 1, Map ID No. 11: Primary Effluent Splitter Box, Map ID No. 13: Vehicle Fueling Station, Map ID No. 14: Wastewater Pump Station, Map ID No. 15: Blower Building No. 2, Map ID No. 18: Bio Reactor Basin No. 3, 4, 5, and 6, Map ID No.28: Sodium Bisuphite Storage Building 1 were developed on the property (CH2M Hill 2003; NETR 2022; UCSB 2022). In 2005, another expansion and upgrade project for existing facilities took place. Map ID No. 14: Wastewater Pump Station, Map ID No. 3: Biogas Tanks, and Map ID No. 20: Filter Influent Pump Station No. 1 were constructed. In 2019, the north half of the Map ID No. 26: Michael Lambert Drying Beds were paved and reallocated for parking (CH2M Hill 2005; NETR 2022; UCSB 2022). Since its initial construction in 1961, the site has grown in multiple phases of expansion to the 60-acre facility which currently contains some 30 buildings and structures. 3.3 Engineering Firm: Pomeroy & Associates (19511965)The Hill Canyon Treatment Plant was designed by engineering firm Pomeroy & Associates in 1961. Doctor Richard D. Pomeroy began his sanitary engineering career at the California Institute of Technology in 1926 and obtained a doctorate in philosophy in 1931 (Bakersfield Californian 1951, p. 20). After graduating, Pomeroy taught as an Associate Professor of Sanitary Engineering at Occidental College and the University of Southern California Bakersfield Californian 1951, p. 20). In 1932, he obtained a position at the Los Angeles County Sanitation District before engaging in private consulting work. In 1950, Pomeroy founded his chemistry and civil engineering firm, Pomeroy & Associates (Los Angeles Evening Citizen News 1945, p. 4; Bakersfield Californian 1951, p. 20). Pomeroy & Associates predominantly worked on water supply, sanitation, and corrosion projects (Bakersfield Californian 1951, p. 20). In 1961, Pasadena-based consulting and civil engineers Pomeroy & Associates hired J. Wynne Davies, a water and sewage treatment expert (Independent Star-News 1961, p. 19). Davies immediately began work on the Hill Canyon Treatment Plant, which was in urgent need of expansion (Ventura County Star 1961a, p. 2). By 1965, the firm had been renamed Leason Pomeroy Associates and had offices in Orange County and in Sacramento (Los Angeles Times 1988, p. 79; Sacramento Bee 2022, p. B8).

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A partial list of the water and sewer management facilities in California designed by Pomeroy & Associates includes:Designed system to cut stormwater entry into sewer system, City of Santa Cruz (1954) (Santa Cruz Sentinel 1954a, p 1)Designed separate sewer and water supply systems, City of Santa Cruz (1954) (Santa Cruz Sentinel 1954b, p. 1).Portions of, City of Los Angeles (1955) (Los Angeles Times 1955, p. 4)Casitas Dam, Ventura River Municipal Water District, Ventura County (1956) (Ventura County Star 1956, p. 1). Ojai City sewage disposal system, City of Ojai (1958) (Ventura County Star 1958, p. 1). Upper Ventura River Valley and Ojai Valley Sewer System, Ventura County (1961) (Ventura County Star 1959, p. 5)Simi Valley Sewer System, Simi Valley (1961) (Ventura County Star 1961b, p. 14)Arroyo Conejo Sewer Trunk Line, Thousand Oaks (1963) (Ventura County Star 1963, p. 36) Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202226

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4 Results of Identification andEvaluation EffortsOne multi-component historic era facility is located in the Built Environment Study Area: the Hill Canyon Treatment Plant. The original portions of the plant were constructed in 1961 and it has been expanded several times over the course of its history. The Hill Canyon Treatment Plant property is located at 9600 San Rosa Road in the City of Thousand Oaks (APNs 552-0-130-015, 520-0-300-115, and 667-0-120-170) and contains eleven buildings and nineteenstructures (refer to Figure 2, Built Environment Study Area). A complete California DPR 523 form recording Hill Canyon Treatment Plant may be found in Appendix B of this report. Table 5 below provides a summary of survey observations, descriptions, including a photograph of each building and/or structure, the year built (if known), a general physical description of the building/structure, and any alterations identified. Circa dates for construction of buildings and structures were chosen by selecting the median year between two aerials photographs dates, whenever aerial photographs were used to estimate the construction.

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IdentifiedAlterationsDudek staff received inspection reports, permits, City resolutions, and condition reports from the City of Thousand Oaks on May 10, 2022, pertaining to Hill Canyon Treatment Plant, 9600 Santa Rosa Road (APNs 552-0-130-015, 520-0-300-115, and 667-0-120-170). Observed alterations are also included in this section, and dates stated if known:1959. Original Construction begins1961. Original Construction finishes, completed features include:- Map ID No. 4: Digestor No. 1, - Map ID No. 5: North Headworks, - Map ID No. 6: Primary Clarifiers 1 and 4, - Map ID No. 8: Cart Garage and Shop Building- Map ID No. 9: Aeration Station 1,- Two large settling ponds - Administrative/Operations Building (now demolished)1966. Annexation to the City of Thousand Oaks (City of Thousand Oaks 1966)- Observed: Map ID No. 6: Primary Clarifier No. 2 constructed1968. Sludge Lagoons Construction (City of Thousand Oaks 1968)1970. Phase I expansion (City of Thousand Oaks. 1970), added features include:- Map ID No. 4: Digester No. 3, - Map ID No. 6: Primary Clarifier No. 3,- Map ID No. 9: Aeration System No. 2, - Map ID No. 12: Secondary Clarifier No. 11977. Phase IB expansion (City of Thousand Oaks 1977; James M. Montgomery Consulting Engineers Inc. 1977), added features include:- Map ID No. 26. Michael Lambert Drying Beds- two new sludge drying beds (now a solar field), - Map ID No. 21: Tertiary Filters Building (actually constructed circa 1979)- Map ID No. 22: Chemical Building, (actually constructed circa 1979)- Map ID No. 23: Maintenance Building No. 1, (actually constructed circa 1979) - Map ID No. 30: Wastewater Reclamation System1983. Phase IB expansion (James M. Montgomery Consulting Engineers Inc. 1983), added features include:- Map ID No. 2: Thickening Building, 1986. Hill Canyon Wastewater Treatment Plant Equalization Basin Lining Project (James M. Montgomery Consulting Engineers Inc. 1986), added features include:- Map ID No. 25: Equalization Basin split drying bed into 2 equalization Basins 1987. Phase IB expansion (James M. Montgomery Consulting Engineers Inc. 1987), added features include:- Map ID No. 19: South Headworks, - Map ID No. 12: Secondary Clarifiers No. 2, and - Map ID No. 17: Filter Backwash Pump Station Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202247
Observed. Circa 1989-1994. Map ID No. 29: Mixed Liquor Channel constructedObserved. Circa 1994-2002. Another expansion Project, no record on file with City (NETR 2022; UCSB 2022)- Map ID No. 1: Operations Building, - Map ID No. 4: Digestor No. 3, - Map ID No. 12: Secondary Clarifiers No. 3, - Map ID No. 20: Filter Influent Pump Station No. 2, - Map ID No. 24: Maintenance Building No. 2, - Map ID No. 27: Dewatering/Generator Building, and 2003. Hill Canyon Wastewater Treatment Plant Expansion/Upgrade Phase II (CH2M Hill 2003), added features include:- Map ID No. 7: Maintenance Storage Building, - Map ID No. 10: Blower Building No. 1, - Map ID No. 11: Primary Effluent Splitter Box, - Map ID No. 13: Vehicle Fueling Station, - Map ID No. 14: Wastewater Pump Station, - Map ID No. 15: Blower Building No. 2, - Map ID No. 18: Bio Reactor Basin No. 3, 4, 5, and 6, - Map ID No. 28: Sodium Bisuphite Storage Building 1, and 2005. Hill Canyon Wastewater Treatment Plant Expansion and Upgrade Phase III (CH2M Hill 2005), added features include:- Map ID No. 3: Biogas Tanks and - Map ID No. 20: Filter Influent Pump Station No. 14.2 National Register of Historic Places/California Register of Historic ResourcesStatement of Significance The Hill Canyon Treatment Plant does not meet any of the criteria for listing in the NRHP or CRHR, either individually or as part of an existing historic district, as demonstrated below. CriterionA/1:Thatareassociatedwitheventsthathavemadeasignificantcontributiontothebroadpatternsofourhistory.Archival research on the Hill Canyon Treatment Plant property indicated that the plant is best understood as part of the broad pattern of wastewater infrastructure development in response to urban and suburban growth in VenturaCounty in the late twentieth and early twenty-first century. As Thousand Oaks was a relatively young community establishedother Southern California cities, which tended to create sewerage and treatment facilities in the 1910s-1930s.Thousand Oaks, once a rural agricultural town, is now a computer and advanced technology hub. The transition began Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202248
that grew rapidly in the post-war and mid-century years in California.In 1961, the Hill Canyon Treatment Plant was established by Conejo Valley Sanitary Company, a subsidiary of the Janss Corporation, to serve the rising need for public sanitation and wastewater management. The City of Thousand Oaks purchased Hill Canyon Treatment Plant in 1961, and in 1966 brought all water and sewer services under city control. Over the course of its history, the Hill Canyon Treatment Plant treated wastewater for approximately 90% of the City of Thousand Oaks, which has more than 127,000 residents. Wastewater facilities like the Hill Canyon Treatment Plant are developed like other municipal utilities to support growing and expanding communities. Although wastewater facilities represent necessary community sustaining infrastructure, they only exist to support an existing community and are merely associated with growth which is not considered a significant historic event and does not rise to the level of consideration of associative historical significance with events that have contributed to board patterns of history. In consideration of these factors, the Hill Canyon Treatment Plant is not eligible under NRHP Criterion A or CRHR Criterion 1.CriterionB/2:Thatareassociatedwiththelivesofpersonssignificantinourpast.To be found eligible under NRHP Criterion B or CRHR Criterion 2 the property has to be directly tied to an important person and the place where that individual conducted or produced the work for which he or she is known. An example of such a property that could be found significant under these Criteria is a famous artists studio where they conducted the work for which they are known or the headquarters building associated with a famous industrialist. The Hill Canyon Treatment Plant is a regional wastewater system that represents the collective efforts of many people who worked at the facility and it is not known to be a place where any historically significant person or group of people conducted or produce work for which they are known. Due to a lack of identified significant associations with important persons in history, the subject property is recommended ineligible under NRHP Criterion B or CRHR Criterion 2. Due to a lack of identified significant associations with important persons in history, Prothero Water Filtration Plant does not appear eligible under NRHP Criterion B or CRHR Criterion 2.CriterionC/3:Thatembodythedistinctivecharacteristicsofatype,period,ormethodofconstruction,orthatrepresenttheworkofamaster,orthatpossesshighartisticvalues,orthatrepresentasignificantanddistinguishableentitywhosecomponentsmaylackindividualdistinction.The Hill Canyon Treatment Plant was designed by Pomeroy & Associates and constructed in 1961 for the Conejo Valley Sanitary Company. Archival research indicates that Pomeroy & Associates primarily designed wastewater treatment plants and sewer systems, but appear to have filled a regional niche where other companies were not operating, rather than having any innovative designs or engineering solutions. Pomeroy & Associates do not appear to be a significant firm in the context of wastewater treatment plants and sewer systems at either the national, state, or local level. Additional research did not uncover a significant body of work or craftsmanship by this firm that . As a wastewater facility, it is comprised of utilitarian buildings and infrastructure commonly found in various jurisdictions throughout the state and nationwide.In consideration of the multiple phases of expansion to support to growing community, the facility lacks a cohesive, identifiable architectural style. The design is devoid of any defining architectural or engineering features and multiple expansions from the 1970s to the 2000s altereddemolished many original components. Further, the Hill Canyon Treatment Plant cannot be considered a representative work of the firm since many of the original buildings and structures have been demolished, expanded, or altered in subsequent plant expansions. Finally, Hill Canyon Treatment Plant does not possess high artistic value, and should not be considered Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202249
representative of a significant and distinguishable entity whose components may lack individual distinctionas the complex is comprised of ubiquitous and utilitarian structures and prefabricated industrial buildings. Consequently, the subject property is recommended not eligible under NRHP Criterion C or CRHR Criterion 3.CriterionD/4:Thathaveyielded,ormaybelikelytoyield,informationimportantinprehistoryorhistory.This report was limited to historical resources that are part of the built environment. NRHP Criterion D and CRHR Criterion 4 generally applies to archaeological resources but may apply to a built environment resource in instances where a resource may contain valuable information about such topics as construction techniques or human activity. Therefore, the built environment components of the subject property are recommended not eligible under NRHP Criterion D and CRHR Criterion 4.4.3 City of Thousand Oaks Significance EvaluationThe Hill Canyon Treatment Plant does not meet any of the criteria for listing in As a City of Thousand Oaks Landmark or Point of Historical Interest. Though the property does contain buildings and structures constructed over 45 years ago, the property, as a whole does not (1)as the property was originally constructed as part of the Conejo Valley Sanitation Company holdings and , as demonstrated above in NRHP/CRHR Criteria A/1 and C/3;(2) Is not associated withcultural heritage, and plays a mundane and ubiquitous role in the development of the city and greater urban community after its founding, as demonstrated above in NRHP/CRHR Criteria A/1; (3) Was not found to be associated with the lives of people important to the history of the City, as demonstrated above in NRHP/CRHR Criteria 2/B;(4) Does not have the potential to yield information important to the prehistory or history of the City, as demonstrated above in NRHP/CRHR Criteria 4/D; and(5) Lacks a distinctive, identifiable building typology or architectural style, readily identifiable to the period of construction, region, nor does it demonstrate a unique method of construction, exemplify the work of a master or possess high artistic value.For all of these reasons Hill Canyon Treatment Plant is not eligible as a local City of Thousand Oaks landmark. The City of Thousand Oaks criteria for Points of Historical Interest are predicated on the idea that (1) a property is no longer extant; (2) a property has been highly altered such that it cannot convey original workmanship or materials; or (3) is the site of a historical event with no distinguishing visual landmarks or characteristics. The Hill Canyon Treatment does not qualify as a local City of Thousand Oaks point of historical interest either. 4.4 Integrity DiscussionNational Register Bulletin 15: How to Apply the National Register Criteria for Evaluation states that the integrity of a property is based upon the historical significance and character-1995, p. 45). As the Hill Canyon Treatment Plant property does not meet any of the required significance Criteria a discussion of integrity is inconsequential and is not required.

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5 Summary of Findings andManagement Recommendations5.1 Summary of FindingsDudek recorded and evaluated the Hill Canyon Treatment Plant property located within the Built Environment Study Area and recommends that the subject property does not meet any eligibility requirement under national, state, or local designation criteria. Therefore, the property is not considered a historical resource under CEQA. There are no built environment properties considered CEQA historical resources located within the Built Environment Study Area. As such the finding for the Project under CEQA is NoImpact.

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6 ReferencesAllen, P.A. 1978.An Historic Study of the Property Known As the M.G.M. Ranch a Planned Community by Shapell Industries Inc.Report No. VN-1527. On File at the South Central Coastal Information Center, California State University, Fullerton. Accessed March 24, 2022.the Bakersfield Californian(Bakersfield, CA). June 5, 1951, pg. 20Bidwell, C.- History Books Division. Held by the Thousand Oaks Library. Bonner, W.1997. Cultural Resources Assessment of the Hill Canyon Regional Recreational Facility, Thousand Oaks, Ca. Report No. VN-1593. On File at the South Central Coastal Information Center, California State University, Fullerton. Accessed March 24, 2022.CH2M Hill. 2003. Hill Canyon Wastewater Treatment Plant Expansion/Upgrade Phase II. Record drawings. Pp. 1-404. Shared with Dudek by the City of Thousand Oaks. CH2M Hill. 2005. Hill Canyon Wastewater Treatment Plant Expansion and Upgrade Phase III. Record drawings. Pp. 1-260. Shared with Dudek by the City of Thousand Oaks. City of Thousand Oaks. 1966. Resolution No. 66-105: A Resolution of the City Council of the City of Thousand Oaks Petitioning the Board of Supervisors of the County of Ventura to Complete Annexation Procedures of Proposed Annexation Number Eleven. Adopted July 12, 1966, by David F. Betts, Thousand Oaks Mayor. File obtained through City of Thousand Oaks Public Records Request. City of Thousand Oaks. 1968. Resolution No. 68-167: A Resolution of the City Council of the City of Thousand Oaks Accepting the Hill Canyon Sewage Treatment Plan Sludge Lagoons Construction. Adopted September 17, 1968, by Alex T. Fiore, Thousand Oaks Mayor. File obtained through City of Thousand Oaks Public Records Request. City of Thousand Oaks. 1970. Resolution No. 70-294: A Resolution of the City Council of the City of Thousand Oaks Accepting the Phase I Expansion Project at the Hill Canyon Treatment Plant. Adopted August 25, 1970, by Charles W. Cohen, Thousand Oaks Mayor. File obtained through City of Thousand Oaks Public Records Request. City of Thousand Oaks. 1977. Administrative Approval, Permit No. DP-77-365: A Resolution of the City Council of the City of Thousand Oaks Accepting the Phase I Expansion Project at the Hill Canyon Treatment Plant. Adopted August 25, 1970, by Charles W. Cohen, Thousand Oaks Mayor. File obtained through City of Thousand Oaks Public Records Request. Thousand Oaks General Plan. Prepared October 2013. Accessed May 6, 2022. https://www.toaks.org/home/showpublisheddocument?id=332 Hill Canyon Treatment Plant Stormwater Diversion Project / Built Environment Inventory and Evaluation Report 12767 #CI 5427MAY 202254
City of Thousand Oaks. 2022. .city-manager-s-office/public-information-office/historyCity of Thousand Oaks Library. 2022a.Hill Canyon Wastewater Treatment Plant: CTO_352; LHP03886.April 21, 2022. https://contentdm.tolibrary.org/digital/collection/p17352coll1/id/181/rec/2City of Thousand Oaks Library. 2022bApril 21, 2022. https://cdm17352.contentdm.oclc.org/digital/collection/p17352coll1/id/44Clewlow, W.C. 1977.Archaeological Resource Survey and Preliminary Impact Assessment of the MGM Ranch Property Thousand Oaks, California. Report No. VN-84, On File at the South Central Coastal Information Center, California State University, Fullerton. Accessed March 24, 2022. Gannett-Fleming. 2020. Hill Canyon Treatment Plant Master Plan. Prepared for City of Thousand Oaks, March 2020. Accessed March 23, 2022, https://www.toaks.org/home/showpublisheddocument?id=33783Hoover, M., H.E. Rensch, E.G. Rensch, and W.N. Abeloe. 2002. Historic Spots in California.5th ed. Stanford, California: Stanford University Press.Independent Star-Newspapers.com: Independent Star-News(Pasadena, CA). December 10, 1961, pg. 43James M. Montgomery Consulting Engineers Inc. 1977. Hill Canyon Wastewater Treatment Plant drawings. Pp. 1-8. On -File obtained through City of Thousand Oaks Public Records Request.James M. Montgomery Consulting Engineers Inc. 1983. Hill Canyon WWTP: Sludge Dewatering drawings. Pp. 1-4. On -James M. Montgomery Consulting Engineers Inc. 1986. Hill Canyon Wastewater Treatment Plant Equalization Basin Lining Project. Record drawings. Pp. 1-31. Shared with Dudek by the City of Thousand Oaks. James M. Montgomery Consulting Engineers Inc. 1987. Hill Canyon Wastewater Treatment Phase 1B Expansion. Record drawings. Pp. 1-145. Shared with Dudek by the City of Thousand Oaks. Newspapers.com: The Los Angeles Evening Citizen News (Hollywood, CA). May 10, 1945, pg. 4. The Los Angeles Times(Los Angeles, CA) May 27, 1955, pg. 4. Los Angeles Times. 1962.Newspapers.com: The Los Angeles Times(Los Angeles, CA) September 23, 1962, pg. 118. Newspapers.com: The Los Angeles Times(Los Angeles, CA) December 7, 1988, pg. 79.

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Maki, M.1997. Phase 1 Archaeological Survey and Impact Assessment of Approximately 4 Linear Miles for the Unit W & F Interceptor Replacement Project Arroyo Conejo Thousand Oaks, Ventura County, California.Report No. VN-1573. On File at the South Central Coastal Information Center, California State University, Fullerton. Accessed March 24, 2022. NETR (Nationwide Environmental Title Research LLC). 2022. Historic Aerial Photographs of Hill Canyon Treatment Plant, Thousand Oaks, CA dating from 1947, 1967, 1978, 1980, 1985, 1989, 1994, 2002, 2005, 2009, 2010, 2012, 2014, 2016, and 2018. Accessed March 2, 2022. https://www.historicaerials.com/viewer.NPS (National Park Service). 1995.Bulletin 15. Accessed March 31, 2022. https://www.nps.gov/nr/publications/bulletins/pdfs/nrb15.pdf.Thousand Oaks Public Records Request. Rosen, M.D. 1976.Conejo Canyons Study.Report No. VN-101, On File at the South Central Coastal Information Center, California State University, Fullerton. Accessed March 24, 2022. The Sacramento Bee(Sacramento, CA).March 13, 2022, pg. 8B. Newspapers.com: The Santa Cruz Sentinel(Santa Cruz, CA). November 9, 1954, pg. 1 Newspapers.com: The Santa Cruz Sentinel(Santa Cruz, CA). September 26, 1954, pg. 1. UCSB (University of California, Santa Barbara). 2022. Historic Aerial Photographs Hill Canyon Treatment Plant, Thousand Oaks, CA dating from 1945, 1947, 1953, 1959, 1961, 1965, 1970, 1977, and 1980. Map & Imagery Laboratory (MIL) UCSB Library, Electronic Resource. Accessed March 2, 2022. http://mil.library.ucsb.edu/ap_indexes/FrameFinder.Ventura County Star. 1956.Newspapers.com: Ventura County Star(Ventura, CA). March 29, 1956, pg. 1. Ventura County Star. 1958.Council and Planners Split on Master Plan for Ojai: Ventura County Star(Ventura, CA). March 18, 1958, pg. 1. Newspapers.com: Ventura County Star(Ventura, CA). October 10, 1959, pg. 5. : Ventura County Star(Ventura, CA). September 9, 1961, pg. 2.

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: Ventura County Star(Ventura, CA). April 25, 1961, pg. 14.: Ventura County Star(Ventura, CA). December 18, pg. 36. WaterZen. 2022. https://waterzen.com/water-providers/city-of-thousand-oaks-water/#:~:text= Established%20in%201964%2C%20the%20City%20of%20Thousand%20Oaks,water%29%20through%20the%20Calleguas%20Municipal%20Water%20District%20%28Calleguas%29.

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Appendix A

1 ARCHITECTURAL HISTORIANKate Kaiser (KAYT KY-zer; she/her) is an architectural historian with 10 yearsexperience as a cultural resource manager in California, Nevada, Oregon, Washington, and Hawaii. Professional Qualification Standards for both architectural history and archaeology. Ms. Kaiser specializes in California Environmental Quality Act (CEQA)compliance, National Historic Preservation Act (NHPA) Section 106 and Section 110 compliance, Historic Resource Evaluation Reports (HRER), historical resource inventories (HRI), environmental impact report (EIR) chapters, Historic American Building Survey (HABS) level documentation, archival research, adverse effects or impacts analysis, cultural landscapes, and geographic information systems (GIS). Recent Dudek Project ExperienceHistoricStructures/SiteReportforConfidentialProject,ConfidentialClient,SantaBarbara,California.Dudek was retained by a private constructioncompany to prepare a Historic Structures/Site Report (HSSR) for a Mid-CenturyModern military property built in the 1950s located in Santa Barbara,California. Dudek conducted archival research and an intensive-level survey ofthe property for historic built environment resources. As part of this study,Dudek prepared a Phase 1 HSSR for the property that included a historiccontext statement and significance evaluation and a Phase 2 HSSR thatconformance review. Ms. Kaiser served as architectural historian and coauthorof the report as well as contributing analysis of CHRIS records search results,reviewing permits, archival research, historical context development,developing building descriptions, and drafting outreach letters to interestedparties. (20192021)OnCallHistoricBuiltEnvironmentServicesCaliforniaDepartmentofWaterResources,VariousLocations,California.Dudek was retained by the California Department of Water Resources to prepare a historic context statement for historic-aged infrastructure related to the State Water Project and Built Environment Inventory and Evaluation Reports for various State Water Project maintenance projects. Over the course of this multiyear project, Dudek is providing technical assistance in creating individual and statewide historical context statements and significance evaluations for State-owned water infrastructure. Ms. Kaiser also provides technical expertise and peer review for historical built environment reports authored by subconsultants. As architectural historian, Ms. Kaiser has coauthored HRERs and findings of effects for the following structures (2020Present): Oroville Dam and spillway (2022)Cedar Springs Dam and spillway (2022)South Bay Aqueduct (2021) Education
University of Oregon
MS, Historic Preservation,
2017
Boston University
BA, Archaeology, 2009
ProfessionalAffiliations
Wrightwood Historical
Society Board Member
Association for
Preservation Technology
Southwest
California Preservation
Foundation
Society for California
Archaeology
National Trust for Historic
Preservation

2 Patterson Dam and reservoir (2021)Clifton Court Forebay (2021)segments of the California Aqueduct (2020-2021)San Luis Field Division Operations and Maintenance Center (2021, 2022)Gianelli Pumping-Generating Plant (2022)Dos Amigos Pumping Plant (2021, 2022)Coalinga Operations and Maintenance Subcenter (2021)B.F. Sisk Dam/San Luis Reservoir Historic District (2021, 2022).On-CallServices,LosAngelesCountyDepartmentofPublicWorks,VariousLocations,California.Dudek was retained by the Los Angeles County Department of Public Works to prepare a historic built environment inventory, evaluation technical reports, and finding of effect statements for historic-aged infrastructure operated by the Department of Public Works as part of larger CEQA compliance efforts. Acting as architectural historian, Ms. Kaiser has coauthored HRERs and findings of effects for the following projects: Santa Anita Debris Dam Seismic Strengthening Project, Colima Road Improvement Project, and Mulholland Highway at Mile Marker 3.22. For all projects, Ms. Kaiser authored the built environment inventory and evaluation technical reports and conducted survey, outreach to interested parties, archival research, historic context development, and other tasks. (2021Present)BuiltEnvironmentInventoryandEvaluationReportforElToroWaterDistrictWaterFiltrationPlantProject,ElToroWaterDistrict,OrangeCounty,California.Dudek was retained by El Toro Water District to prepare an inventory and evaluation report for the Prothero Water Filtration Plant, located in the City of Mission Viejo. The project proposedto demolish the existing 1963-1972 buildings and structures and construct new facilities at the property. Preparation of the report involved survey, archival research, historic context development, and a historical significance evaluation. Dudek recommended that Prothero Water Filtration Plant was ineligible for listing as a historical resource and evaluated potential adverse effects to surrounding properties. (2022)As-NeededEnvironmentalComplianceServices,LosAngelesDepartmentofWaterandPower,California.Dudek provides on-call environmental services to the Los Angeles Department of Water and Power (LADWP). As part of this contract, Dudek has prepared CEQA-Plus documentation (CEQA and Section 106 of the NHPA) for a range of infrastructure projects, including groundwater treatment facilities, power plants, electrical transmission and distribution facilities, reservoirs, pipelines, roadways, and other related infrastructure. When LADWP project funding sources include the California State Water Resources CoFund, applications for funding must include proof of CEQA compliance and of compliance with federal requirements through CEQA-Plus. Preparation of each CEQA-Plus report involves extensive archival research;historic context development; building descriptions; historical significance evaluations under all applicable NRHP, CRHR, and Los Angeles Historic-Cultural Monuments designation criteria; and DPR forms for each property/resource.Cultural Resources Technical Reports include the following.Textile Distributing Station 16 Expansion Project, LADWP, California. (2022)Western District Yards Rehabilitation Project, LADWP, California. (2019)City Trunkline South Project, LADWP, California. (2019)Valley Generating Station Project, LADWP, California. (2019)De Soto Tanks Project, LADWP, California. (2019)Tujunga Spreading Grounds Enhancement Project, LADWP, California. (2018) 3 West Los Angeles District Yard Project, LADWP, California. (2017)HistoricalResourcesTechnicalReportsfortheMunicipalWaterwaysMaintenanceProjectCEQAComplianceandU.S.ArmyCorpsofEngineersPermitting,CityofSanDiegoTransportationandStormwaterDepartments,California.Dudek developed the Municipal Waterways Maintenance Plan in close coordination with the City of San Diego Transportation and Stormwater Departmentsfacility maintenance program. The Municipal Waterways Maintenance Plan details the planned maintenance activities, specific facility maintenance locations, and site-specific facility maintenance plans or technical summaries for stormwater conveyance channels, ditches, structures, and basins throughout eight watersheds within the CTechnical Report for:Alvarado Canyon Creek Mission Gorge (Facility No. 4-07-011; Mission Gorge 4) Channel Maintenance Project (2020)Chollas Creek, National 1 and 2 (Facility No. 5-04-004 and 005) Channel Maintenance Project (2021), and Green Valley Creek, Pomerado 2 (Facility No. 1-04-003) Channel Maintenance Project (2022).HistoricalResourcesTechnicalReportsfortheIrvineRanchWaterDistrictFlemingZone8ReservoirandPumpStationImprovementsProject,IrvineRanchWaterDistrict,UnincorporatedOrangeCounty,California.Dudek was retained by the Irvine Ranch Water District to prepare a Historical Resources Technical Report for the proposed Fleming Zone 8 Reservoir and Pump Station Improvements Project in the Santiago Canyon area of unincorporated Orange County. The project proposed to demolish the current reservoir, pump station, and associated buildingsand construct a new reservoir, pump station, storage building, and associated pipelines and utilities. Ms. Kaiser provided pedestrian survey, background research, technical expertise, and report review. (2021)HistoricContextStatementforReservoirs,CityofSanDiegoPublicUtilitiesDepartment,California.Dudek was retained by the City of San Diego Public Utilities Department to complete a survey and historic context statement for the Cserved as architectural historian, author of the historic context statement, and coauthor of individual historic resource reports for the 10 reservoir complexes that contribute to a historic district. Dudek also prepared detailed impact assessments for proposed modification to dams, as required by the California Division of Safety of Dams. The project involved evaluation of 10 dam complexes and conduit for historical significance in consideration of NRHP, CRHR, and City designation criteria and integrity requirements, and required extensive archival research and pedestrian survey. (2020)OlympicWellFieldRestorationandArcadiaWaterTreatmentPlantExpansionProject,CityofSantaMonicaPublicWorksDepartment,California.Dudek was retained by the City of Santa Monica Public Works Department, Water Resources Division, to complete a historical resource technical report for the Olympic Wellfield Restoration and Arcadia Water Treatment Plant Expansion Project.Ms. Kaiser served as architectural historian and author of the historical resource technical report and EIR chapter. Preparation of the report involved site recordation, extensive archival research, historic context development, building and structure development descriptions for 25 buildings and structures at the Arcadia Water Treatment Plant and a well along Olympic Boulevard, historical significance evaluations, and DPR forms for each building and structure of the project. The project proposed to demolish several underutilized buildings and structures as part of an overarching, multicomponent project to add new wells to the Olympic Well Field, construct a new 16-inch pipeline connecting the Olympic Well Field to a new Olympic Advanced Water Treatment Facility, and expand the Arcadia water Treatment Plant to handle additional flows. (20192020) 1 ARCHITECTURAL HISTORIANErin Jones (AIR-in JO-nes; she/her) is a highly committed, well-qualified cultural resource manager with experience co-authoring National Historic Landmark nominations, authoring historic context statements, California Department of Parks and Recreation (DPR) 523 forms, and architectural building descriptions. Ms. Jones has demonstrated experience with the National Historic Preservation Act (NHPA), the National Environmental Policy Acy (NEPA), the California Environmental Quality Act (CEQA), Section 106, Historic Resource Evaluation Reports (HRER), Historical Resource Inventories (HRI), Environmental Impact Report (EIR) chapters, Historic American Building Survey (HABS) level documentation, reconnaissance and intensive level surveys, archival research, cultural landscapes, and geographic information systems Standards for architectural history. MasterPlan,CaliforniaStateUniversity,MontereyBay,Seaside,California.Dudek was retained by California State University (CSU), Monterey Bay, to complete a built environment inventory and evaluation report in support of the Master Plan EIR. This study involved archival research, survey, recordation, and evaluation of 11 campus buildings more than 45 years old that are proposed for demolition/su-Term Jones provided assistance conducting background research and drafting historic context statements for this project. (2021- present)HistoricalResourcesInventoryandEvaluationReportforthe1535-1575IndustrialAvenueWarehouseProject,SanJose,California.Ms. Jones worked as an architectural historian and author of the Historical Resources Inventory and Evaluation Report for the 1535-1575 Industrial Avenue Warehouse Project which proposes to demolish the existing buildings on the Project site and construct a single-story 71,550 square-foot concrete tilt-up building with a loading dock and adjacent parking lot.Ms. Jones role in the project includes the review of the California Historical Resources Information Systems (CHRIS) records search; conducting a pedestrian survey of the Project area; building development and archival research; authoring the historic context statement; evaluation of property for the NRHP, CRHR, California Historical Landmark, and local eligibility criteria and integrity requirements; an assessment of impacts to historical resources in compliance with CEQA Guidelines and the City of San JoséHistoric Preservation Ordinance.(2021)1400ThompsonAvenueProject,SantaCruzCounty,California.Served as the architectural historian and co-author of the Historic Resources Evaluation Report for the 1400 Thompson Avenue Project. The project proposedto demolish the existing buildings and subdivide the site into four new parcels that will be sold and developed individually. Dudek was retained by a private homeowner to complete the report in support of the proposed project. al research; authoring the historic context; evaluation of property for the NRHP, CRHR, California Historical Landmark, and local eligibility Education
California State University,
Sacramento
Master of Arts Public
History with Honors,
Spring 2021
University of Oregon
Bachelor of Arts History,
Fall 2017

2 criteria and integrity requirements; an assessment of impacts to historical resources in compliance with CEQA; and the preparation of the accompanying DPR forms. (2021)PhaseIHistoricResourcesTechnicalReport,Building7045,DevereuxGymnasium,WestCampus,UniversityofCalifornia,SantaBarbara.Ms. Jones acted as an architectural historian and co-author of the Cultural Resources Inventory and Evaluation Report for the Phase I Historic Resources Technical Report (report), Building 7045, Devereux Gymnasium on the West Campus of University of California, Santa Barbara. Dudek was retained by the University of California, Santa Barbara (UCSB) to complete the report funded by federal funds from the National Endowment for the Humanities (NEH), making it subject to federal review under Section 106 of the National Historic Preservation Act of 1966 (16U.S.C. 470f), the regulations found at 36 CFR Part 800, and pursuant to the National Programmatic Agreement among the National Endowment for the Arts, National Conference of State Historic Preservation Officers, and the Advisory Council on Historic Preservation Regarding Implementing Section 106 of the National Historic Preservation Act for National Endowment for the Arts Grants (Section 106). The Project is also subject to review under CEQA and Public Resources Code (PRC) Sections 5024 and 5024.5 for state-owned resources. The purpose of this HRTR is to determine if the Project has the potential to affect historic properties pursuant to Section 106 or would impact any historical resources pursuant to CEQA (hereafter referred to as historic properties). Ms. Jonearchival and building development research for Building 7045, Devereux Gymnasium; co-authoring of the historic context covering the development of the Devereux School and UCSB campus; writing building descriptions; evaluating the building for the NRHP, CRHR, California Historical Landmark (CHL), and Santa Barbara County local eligibility criteria and integrity requirements; and the preparation of the accompanying DPR forms. (2021)BuiltEnvironmentInventoryandEvaluationfortheNorthgateTownSquareProject,SanRafael,California.Ms. Jones served as an architectural historian and co-author of the Built Environment Inventory and Evaluation for the Northgate Town Square Project. Dudek was retained by Merlone Geier Management, LLC to prepare a Built Environment Inventory and Evaluation Report for the proposed Northgate Town Square Project (Project). Ascurrently planned, the proposed Project consists of the phased redevelopment of the existing 44.76-acre Northgate Mall complex and stand-alone buildings (Project site). This report was prepared in conformance with California Environmental Quality Act (CEQA) Guidelines Section 15064.5 for historical resources, and all applicable local guidelines and regulations to assess potential Project-related impacts to built environment resources under CEQA.role in the preparation report included biographical research for the architects that contributed to the building of Northgate Town Square and the preparation of a DPR 523 for the Northgate complex and a continuation DPR523 form for an adjacent neighborhood. (2021).650NorthKingRoad,SantaClaraCounty,California.Served as the architectural historian and author of the Standalone DPR 523 form for the 650 North King Road Project. Ms. Jones conducted archival, map, aerial, property, and building development, research; conducted an evaluation of property for the NRHP, CRHR, California Historical Landmark, and local eligibility criteria and integrity requirements; an assessment of impacts to historical resources in compliance with CEQA; and prepared the DPR 523 form (2021)Historic Vernacular Landscape. 1 HISTORIC BUILT ENVIRONMENT LEADKathryn Haley (KATH-rin HAY-lee; she/her) is a historic built environment resource specialist/architectural historian with 19 yearsprofessional experience in historic/cultural resource management. Ms. Haley has worked on a wide variety of projects involving historic research, field inventory, and site assessment conducted for compliance with Section 106 of the National Historic Preservation Act (NHPA), National Environmental Policy Act (NEPA), and California Environmental Quality Act (CEQA). Ms. Haley specializes in the California Register of Historical Resources (CRHR); the National Register of Historic Places (NRHP);and evaluations of built environment resources, including water managementstructures (levees, canals, dams, sewers plants and maintenance centers, and ditches), and linear resources (railroad alignments, roads, and bridges). She has prepared numerous Historic Resources Evaluation Reports (HRERs) and Historic Property Survey Reports (HPSRs) for the California Department of Transportation (Caltrans). Professional Qualification Standards for historian and architectural historian. Moreover, Ms. Haley has served as project manager, coordinator, quality assurance/quality control (QA/QC), historian, and researcher for a wide variety of projects. She is also experienced in the preparation of Historic American Building Survey (HABS), Historic American Engineering Record (HAER), and Historic American Landscape Survey (HALS) documents, as well as the preparation for National Register nominations.On-CallServicesforDepartmentofWaterResources,OperationsandMaintenanceDivision,StateofCalifornia.Division (O&M), to assist in a wide range of on-going environmental compliance efforts. Under this on-call contract, Ms. Haley serves as project manager for a task order focused on assisting DWR in efforts to streamline cultural resources environmental documentation for O&M projects. Dudek is also preparing several built environment technical reports for several projects under this contract. She provided senior-level guidance throughout each task order and QA/QC on a standardized historic context statement for State Water Project (SWP), as well as Historical Resources Technical Reports for various SWP maintenance projects. Technical reports have been prepared for O&M projects at the following structures (2020Present): Oroville Dam and spillway (2022)Cedar Springs Dam and spillway (2022)South Bay Aqueduct (2021)Patterson Dam and reservoir (2021)Clifton Court Forebay (2021)segments of the California Aqueduct (2020-2021) Education
California State University,
Sacramento MA,
Public History, 2004
California State University,
Sacramento BA,
History, 2001
ProfessionalAffiliations
California Council for the
Promotion of History
(former Treasurer)
California Preservation
Foundation

2 San Luis Field Division Operations and Maintenance Center (2021, 2022)Gianelli Pumping-Generating Plant (2022)Dos Amigos Pumping Plant (2021, 2022)Coalinga Operations and Maintenance Subcenter (2021)B.F. Sisk Dam/San Luis Reservoir Historic District (2021, 2022).LagunaCreekDiversionRetrofitProject,CEQAComplianceandU.S.ArmyCorpsofEngineerspermitting,CityofSantaCruz,BonnyDoon,California.As lead architectural historian, Haley co-authored the Cultural Resources Inventory, Evaluation and Finding of Effect Report for the Laguna Creek Diversion Retrofit Project. The purpose of the project is to retrofit the existing 1890 Laguna Creek Diversion Facility in Bonny Doon, California with a new intake and sediment control system. The significance evaluation determined that the Laguna Creek Dam appears individually eligible as a historic resource/property under NRHP/CRHR Criterion A/1, and Santa Cruz County Criterion 2 as a well-preserved masonry water management structure dating to 1890. It is a physical example of pioneering water management infrastructure in California and is significant for its association with early advances in water management water distribution system. All other associated facility buildings and structures were found not eligible under all NRHP , CRHR, and local designation criteria, and the project effects assessment recommends that the project would have a less than significant impact on historical resources (CEQA)/no adverse effect on historic properties (NHPA). (20202021)HistoricResourcesComplianceReportfortheCrowtherSewerPipelineProject,CityofPlacentia,OrangeCounty,California.The City of Placentia proposes to upsize the existing sewer pipeline under Crowther Avenue, Placentia Avenue, and Orangethorpe Avenue by constructing a completely independent pipeline parallel to the existing pipeline, which would be capped and left in place once the new pipeline is completed. All cultural resources work was conducted according to Caltrans guidelines for compliance with CEQA. Provided QA/QC for the Historic Resources Compliance Report. (2020Ongoing)SantaCruzWharfMaintenanceProjectCEQAComplianceandU.S.ArmyCorpsofEngineerspermitting,CityofSantaCruz,California.The Dudek built environment team conducted fieldwork and co-authored the Evaluation and Finding of Effect Report for the Santa Cruz Wharf Maintenance Project. The report was prepared in compliance with Section 106 and in support of the permitting process with the U.S. Army Corps of Engineers (ACOE). Haley co-authored all documentation related to the Wharf, including the significance evaluation that recommended the Wharf as eligible under NRHP Criterion A for its continued associations with the industrial development, transportation, commerce, and recreation development of Santa Cruz and under Criterion C as a distinctive engineering structure known to be the longest wooden pier structure located along the United States west coast. Additionally, a detailed effects assessment determined that the proposed Wharf Maintenance project would have a less than significant impact on historical resources (CEQA)/no adverse effect on historic properties (Section 106). Provided senior-level guidance throughout the project and QA/QC on the technical report. (2020)MunicipalWaterwaysMaintenanceProjectCEQAComplianceandACOEpermitting,CityofSanDiego,California.Dudek developed the Municipal Waterways Maintenance Plan (MWMP) in close coordination with the City of San -going stormwater facility maintenance program. The MWMPdetails the planned maintenance activities, specific facility maintenance locations, biological compensatory mitigation sites, agency permitting procedures, and includes site-specific facility maintenance plans and/or technical summaries for stormwater conveyance channels, ditches, structures, and basins throughout eight including cultural resources as one of the associated technical studies. Provided senior-level guidance on built environment resources for the project and QA/QC on the technical documentation. (2019Ongoing.)

Appendix B DPR Form: Hill Canyon Water Treatment Plant

Page 1 ends

DPR 523A (9/2013) *Required information
State of California - The Resources AgencyPrimary #DEPARTMENT OF PARKS AND RECREATION HRI # PRIMARY RECORDTrinomial NRHP Status Code 6Z Other Listings Review Code Reviewer Date *P2. Location: Not for Publication Unrestricted *a. County Ventura and (P2c, P2e, and P2b or P2d. Attach a Location Map as necessary.) *b. USGS 7.5' Quad Newbury Park, Calif. Date 2015 T 02N ; R 19W, 20W of Sec 36, 36 ; San Bernadino B.M.c. Address 9600 Santa Rosa Road City Camarillo Zip 93012 d. UTM: Zone 11S, 323120.85 mE/ 3787636.08 mN (northeast corner); Zone 11S , 323024.32 mE/ 3787657.32 mN (northwest corner); Zone 11S , 323037.56 mE/ 3787220.09 mN (southeast corner); Zone 11S , 322636.74 mE/ 3787094.13 mN (southwest corner) e. Other Locational Data: (e.g., parcel #, directions to resource, elevation, decimal degrees, etc., as appropriate)Parcel Numbers: 552-0-130-015, 520-0-300-115, and 667-0-120-170 Elevation: 278 to 301 feet amsl Decimal Degrees (centroid): 34.210883°, -118.923410° *P3a. Description: (Describe resource and its major elements. Include design, materials, condition, alterations, size, setting, and boundaries)The Hill Canyon Treatment Plant was first developed in 1961 but expanded continuously throughout the late twentieth and early twenty-first centuries. *(See Continuation Sheet) P3b. Resource Attributes: (List attributes and codes) HP9. Public utility building; HP11. Engineering structure *P4. Resources Present: Building Structure Object Site District Element of District Other (Isolates, etc.) P5b. Description of Photo: (view, date, accession #) Overview of the Hill Canyon Treatment Plant facility. View facing south (IMG_7468). *P6. Date Constructed/Age and Source: Historic Prehistoric Both 1961 (Bidwell 1989, p. 49; Ventura County Star-Free Press 1961, p. 2 *P7. Owner and Address: City Of Thousand Oaks 2100 Thousand Oaks Boulevard Thousand Oaks, California 91362 *P8. Recorded by: (Name, affiliation, and address) Kate Kaiser MSHP Dudek 38 N. Marengo, Pasadena, CA 91101 *P9. Date Recorded: 3/23/2022 *P10. Survey Type: (Describe)Intensive *P11. Report Citation: (Cite survey report and other sources, or enter "none.") Kaiser, Kate, Erin Jones, and Katie Haley. 2022. Built Environment Inventory and Evaluation Report for Hill Canyon Treatment Plant Stormwater Diversion Project. Prepared May 2022 for City of Thousand Oaks. *Attachments: NONE Location Map Continuation Sheet Building, Structure, and Object Record Archaeological Record District Record Linear Feature Record Milling Station Record Rock Art Record Artifact Record Photograph Record Other (List):

P5a. Photograph or Drawing (Photograph required for buildings, structures, and objects.)

*Resource Name or # (Assigned by recorder) Hill Canyon Treatment Plant *NRHP Status Code 6Z Page 2of28 DPR 523B (9/2013) *Required information
State of California - The Resources AgencyPrimary # DEPARTMENT OF PARKS AND RECREATION HRI# BUILDING, STRUCTURE, AND OBJECT RECORD (This space reserved for official comments.) (Sketch Map with north arrow required.) B1. Historic Name: Hill Canyon Wastewater Treatment Plant B2. Common Name: Hill Canyon Treatment Plant B3. Original Use: Wastewater treatment B4. Present Use: Wastewater treatment *B5. Architectural Style: No Specific style noted *B6. Construction History: (Construction date, alterations, and date of alterations)*(See Continuation Sheet) *B7. Moved? No Yes Unknown Date: Original Location: *B8. Related Features:None noted B9a. Engineer: Pomeroy & Associates b. Builder: unknown *B10. Significance: Theme n/a Area n/a Period of Significance n/a Property Type n/a Applicable Criteria n/a (Discuss importance in terms of historical or architectural context as defined by theme, period, and geographic scope. Also address integrity.)The Hill Canyon Treatment Plant does not meet any of the criteria for listing in the NRHP or CRHR, either individually or as part of an existing historic district, nor does it meet local criteria to be considered as a City of Thousand Oaks Landmark or Point of Historical Interest, as demonstrated in the continuation sheets below. *(See Continuation Sheet) B11. Additional Resource Attributes: (List attributes and codes) *B12. References:*(See Continuation Sheet) B13. Remarks: *B14. Evaluator: Kate G. Kaiser, MSHP *Date of Evaluation: 5/20/2022

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DPR 523J (9/2013) *Required information
State of California - The Resources Agency Primary # DEPARTMENT OF PARKS AND RECREATIONHRI# LOCATION MAPTrinomial

DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATIONHRI # Trinomial CONTINUATION SHEET Property Name: ___ Hill Canyon Treatment Plant _____________________________________________________ Page 19 of 28Map ID No. 24: Maintenance Building No. 2, Map ID No. 27: Dewatering/Generator Building, and 2003. Hill Canyon Wastewater Treatment Plant Expansion/Upgrade Phase II (CH2M Hill 2003), added features include: Map ID No. 7: Maintenance Storage Building, Map ID No. 10: Blower Building No. 1, Map ID No. 11: Primary Effluent Splitter Box, Map ID No. 13: Vehicle Fueling Station, Map ID No. 14: Wastewater Pump Station, Map ID No. 15: Blower Building No. 2, Map ID No. 18: Bio Reactor Basin No. 3, 4, 5, and 6, Map ID No. 28: Sodium Bisuphite Storage Building 1, and 2005. Hill Canyon Wastewater Treatment Plant Expansion and Upgrade Phase III (CH2M Hill 2005), added features include: Map ID No. 3: Biogas Tanks and Map ID No. 20: Filter Influent Pump Station No. 1 B10. Significance (Continued): Historical Background for the Hill Canyon Treatment Plant As the Conejo Valley and Thousand Oaks regions continued to develop in the mid-twentieth century, the need for a centralized wastewater treatment facility was apparent as community growth outpaced the abilities of private septic tanks, the most common method of waste disposal in the region. As a result, a private company called the Conejo Valley Sanitary Company was formed, and permits were acquired to build a wastewater plant and sewer connections for the communities of Newbury Park and Thousand Oaks. Pomeroy & Associates, a Pasadena engineering firm specializing in wastewater design and studies, topography that allows wastewater to be pulled by gravity through two mainlines into the treatment plant, minimizing the electrical and environmental clean-up costs for Thousand Oaks. Janss Corp. and California Lutheran College donated two million dollars to fund the development of the Hill Canyon Treatment Plant (Los Angeles Times 1962, p. 118; Bidwell 1989, p. 49; Ventura County Star 1961, p. 2). The plant was completed in 1961, and originally included nine buildings and structures: Map ID No. 4: Digestor No. 1,Map ID No. 5: North Headworks, Map ID No. 6: Clarifiers 1, 2, and 4, Map ID No. 8: the Cart Garage and Shop Building,and Map ID No. 9: Aeration Station 1 (Exhibit 1) that are still present at the site. Two large settling ponds and several non-extant buildings were also part of this original phase of construction (Exhibit 2). Initially, the Hill Canyon Treatment Plant was designed to serve up to 90,000 people. After its incorporation in 1964, City of Thousand Oaks acquired the Hill Canyon Treatment Plant on July 1, 1966, from the Conejo Valley Sanitary Company. Average daily flow design capacity of the plant started around 4 MGD in the late 1960s. The same year, the City hired firm Pomeroy & Associates to add Sludge Dewatering Facilities to the Hill Canyon Plant, just south of the main activity area. This project was completed by 1968. (Bidwell 1989, p. 49; City of Thousand Oaks 1966; City of Thousand Oaks 2022; Gannett-Fleming 2020, p. 1-1; NETR 2022; Pomeroy & Associates 1966, pp.1-7; Ventura County Star-Free Press 1961, p. 2; UCSB 2022).

Exhibit 1. Hill Canyon Treatment Plant facilities under construction c. 1960. Source: City of Thousand Oaks Library 2022a. Exhibit 2. 1967 photograph of the Hill Canyon Treatment Plant taken from the MGM property, view facing south. Source: City of Thousand Oaks Library 2022b.

DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATIONHRI # Trinomial CONTINUATION SHEET Property Name: ___ Hill Canyon Treatment Plant _____________________________________________________ Page 21 of 28Since the initial 1960s construction the City completed three major expansion projects. In 1970, the Phase I Expansion Project for Hill Canyon Treatment plant was approved by the City Council and Mayor. The Phase I construction was developed directly south of the original building complex, included Map ID No. 4: Digester No. 3, Map ID No. 5: North Headworks, Map ID No. 6: Primary Clarifier No. 3, Map ID No. 9: Aeration System No. 2, and Map ID No. 12: Secondary Clarifier No. 1. At the time, domestic, commercial, and industrial customers in the City of Thousand Oaks generated an average of eight million gallons of wastewater per day. The City of Thousand Oaks prepared for continued suburban growth, the approved a treatment plan expansion that accounted for the storage and treatment of fourteen million gallons of wastewater per day (City of Thousand Oaks 1970; Bidwell 1989, p. 47; NETR 2022; UCSB 2022). In 1977, another expansion project was approved by the City, called Phase 1B. Phase 1B began in 1977 and consisted of multiple projects which extended to 1987. In 1977 the improvements consisted of expanding the property further south and creating two new sludge drying beds (now a solar field), and preparation for Map ID No. 21, Tertiary Filters Building Map ID No. 22. Chemical Building, Map ID No. 23 Maintenance Building No. 1, and Map ID No. 30, the Wastewater Reclamation System (City of Thousand Oaks 1977; James M. Montgomery Consulting Engineers Inc 1977; NETR 2022; UCSB 2022). Phase 1B Expansion Project continued into the 1980s. In 1983, Map ID No. 2: Thickening Building, then called a In 1986 and again in 1987, the plant was expanded again to contain and treat over nine million gallons of sewage and wastewater per day and served 29,000 people. Facilities associated with screening, grit removal, two rounds of removing solid waste, nutrient removal, multimedia filtration, disinfection, and dichlorination were developed. The treated water was discharged into Calleguas Creek, which runs north to south and terminates at the Pacific Ocean at Naval Base Fort Mugu. Solids are buried at the Simi Valley landfill (Bidwell 1989, p. 63; City of Thousand Oaks 2022). By 1987, facilities associated with screening, grit removal, two rounds of removing solid waste, nutrient removal, multimedia filtration, disinfection, and de-chlorination were developed. In 1987, Map ID No. 19: South Headworks, Map ID No. 12: Secondary Clarifiers No. 2, and Map ID No. 17: Filter Backwash Pump Station were constructed (James M. Montgomery Consulting Engineers Inc 1983, 1986, 1987; NETR 2022; UCSB 2022). Between 1989 and 1994 Map ID No. 29: Mixed Liquor Channel was constructed. In between 1994 and 2002 another plant expansion took place and Map ID No. 1: Operations Building, Map ID No. 4: Digestor No. 3, Map ID No. 12: Secondary Clarifiers No. 3, Map ID No. 20: Filter Influent Pump Station No. 2, Map ID No. 24: Maintenance Building No. 2, Map ID No.27: Dewatering/Generator Building, and Map ID No. 25: Flow Equalization Basin No. 1 and 2 were built (NETR 2022; UCSB 2022). In 2003, the plant was expanded again, and Map ID No. 7: Maintenance Storage Building, Map ID No. 10: Blower Building No. 1, Map ID No. 11: Primary Effluent Splitter Box, Map ID No. 13: Vehicle Fueling Station, Map ID No. 14: Wastewater Pump Station, Map ID No. 15: Blower Building No. 2, Map ID No. 18: Bio Reactor Basin No. 3, 4, 5, and 6, Map ID No. 28: Sodium Bisuphite Storage Building 1 were developed on the property (CH2M Hill 2003; NETR 2022; UCSB 2022). In 2005, another expansion and upgrade project for existing facilities took place. Map ID No. 14: Wastewater Pump Station,Map ID No. 3: Biogas Tanks, and Map ID No. 20: Filter Influent Pump Station No. 1 were constructed. In 2019, the north half of the Map ID No. 26 Michael Lambert Drying Beds were paved and reallocated for parking (CH2M Hill 2005; NETR 2022; UCSB 2022). Since its initial construction in 1961, the site has grown in multiple phases of expansion to the 60-acre facility which currently contains some 30 buildings and structures.

DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATIONHRI # Trinomial CONTINUATION SHEET Property Name: ___ Hill Canyon Treatment Plant _____________________________________________________ Page 22 of 28Engineering Firm: Pomeroy & Associates (19511965) The Hill Canyon Treatment Plant was designed by engineering firm Pomeroy & Associates in 1961. Doctor Richard D. Pomeroy began his sanitary engineering career at the California Institute of Technology in 1926 and obtained a doctorate in philosophy in 1931 (Bakersfield Californian 1951, p. 20). After graduating, Pomeroy taught as an Associate Professor of Sanitary Engineering at Occidental College and the University of Southern California (Bakersfield Californian 1951, p. 20). In 1932, he obtained a position at the Los Angeles County Sanitation District before engaging in private consulting work. In 1950, Pomeroy founded his chemistry and civil engineering firm, Pomeroy & Associates (Los Angeles Evening Citizen News 1945, p. 4; Bakersfield Californian 1951, p. 20). Pomeroy & Associates predominantly worked on water supply, sanitation, and corrosion projects (Bakersfield Californian 1951, p. 20). In 1961, Pasadena-based consulting and civil engineers Pomeroy & Associates hired J. Wynne Davies, a water and sewage treatment expert (Independent Star-News 1961, p. 19). Davies immediately began work on the Hill Canyon Treatment Plant, which was in urgent need of expansion (Ventura County Star 1961a, p. 2). By 1965, the firm had been renamed Leason Pomeroy Associates and had offices in Orange County and in Sacramento (Los Angeles Times 1988, p. 79; Sacramento Bee 2022, p. B8). A partial list of the water and sewer management facilities in California designed by Pomeroy & Associates includes: Designed system to cut stormwater entry into sewer system, City of Santa Cruz (1954) (Santa Cruz Sentinel 1954a, p 1) Designed separate sewer and water supply systems, City of Santa Cruz (1954) (Santa Cruz Sentinel 1954b, p. 1). s Times 1955, p. 4) Casitas Dam, Ventura River Municipal Water District, Ventura County (1956) (Ventura County Star 1956, p. 1). Ojai City sewage disposal system, City of Ojai (1958) (Ventura County Star 1958, p. 1). Upper Ventura River Valley and Ojai Valley Sewer System, Ventura County (1961) (Ventura County Star 1959, p. 5) Simi Valley Sewer System, Simi Valley (1961) (Ventura County Star 1961b, p. 14) Arroyo Conejo Sewer Trunk Line, Thousand Oaks (1963) (Ventura County Star 1963, p. 36) National Register of Historic Places/California Register of Historic Resources Statement of Significance The Hill Canyon Treatment Plant does not meet any of the criteria for listing in the NRHP or CRHR, either individually or as part of an existing historic district, as demonstrated below. Criterion A/1: That are associated with events that have made a significant contribution to the broad patterns of our history. Archival research on the Hill Canyon Treatment Plant property indicated that the plant is best understood as part of the broad pattern of wastewater infrastructure development in response to urban and suburban growth in Ventura County in the late twentieth and early twenty-first century. As Thousand Oaks was a relatively young community established in 1965, tCalifornia cities, which tended to create sewerage and treatment facilities in the 1910s-1930s. Thousand Oaks, once a

DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATIONHRI # Trinomial CONTINUATION SHEET Property Name: ___ Hill Canyon Treatment Plant _____________________________________________________ Page 23 of 28rural agricultural town, is now a computer and advanced technology hub. The transition began in the 1950s when the Janss in the post-war and mid-century years in California. In 1961, the Hill Canyon Treatment Plant was established by Conejo Valley Sanitary Company, a subsidiary of the Janss Corporation, to serve the rising need for public sanitation and wastewater management. The City of Thousand Oaks purchased Hill Canyon Treatment Plant in 1961, and in 1966 brought all water and sewer services under city control. Over the course of its history, the Hill Canyon Treatment Plant treated wastewater for approximately 90% of the City of Thousand Oaks, which has more than 127,000 residents. Wastewater facilities like the Hill Canyon Treatment Plant are developed like other municipal utilities to support growing and expanding communities. Although wastewater facilities represent necessary community sustaining infrastructure, they only exist to support an existing community and are merely associated with growth which is not considered a significant historic event and does not rise to the level of consideration of associative historical significance with events that have contributed to board patterns of history. In consideration of these factors, the Hill Canyon Treatment Plant is not eligible under NRHP Criterion A or CRHR Criterion 1. Criterion B/2: That are associated with the lives of persons significant in our past. To be found eligible under NRHP Criterion B or CRHR Criterion2 the property has to be directly tied to an important person and the place where that individual conducted or produced the work for which he or she is known. An example of such a property that could be found significant under these Criteria is a famous artists studio where they conducted the work for which they are known or the headquarters building associated with a famous industrialist. The Hill Canyon Treatment Plant is a regional wastewater system that represents the collective efforts of many people who worked at the facility and it is not known to be a place where any historically significant person or group of people conducted or produce work for which they are known. Due to a lack of identified significant associations with important persons in history, the subject property is recommended ineligible under NRHP Criterion B or CRHR Criterion 2. Due to a lack of identified significant associations with important persons in history, Prothero Water Filtration Plant does not appear eligible under NRHP Criterion B or CRHR Criterion 2. Criterion C/3: That embody the distinctive characteristics of a type, period, or method of construction, or that represent the work of a master, or that possess high artistic values, or that represent a significant and distinguishable entity whose components may lack individual distinction. The Hill Canyon Treatment Plant was designed by Pomeroy & Associates and constructed in 1961 for the Conejo Valley Sanitary Company. Archival research indicates that Pomeroy & Associates primarily designed wastewater treatment plants and sewer systems, but appear to have filled a regional niche where other companies were not operating, rather than having any innovative designs or engineering solutions. Pomeroy & Associates do not appear to be a significant firm in the context wastewater treatment plants and sewer systems at either the national, state, or local level. Additional research did not uncover a significant body of work or craftsmanship by this firm that would elevate the firm to the level . As a wastewater facility, it is comprised of utilitarian buildings and infrastructure commonly found in various jurisdictions throughout the state and nationwide. In consideration of the multiple phases of expansion to support to growing community, the facility lacks a cohesive, identifiable architectural style. The design is devoid of any defining architectural or engineering features and multiple expansions from the 1970s to the 2000s demolished many original components. Further, the Hill Canyon Treatment Plant cannot be considered a representative work of the firm since many of the original buildings and structures have been

DPR 523L (9/2013) *Required information
State of California - The Resources Agency Primary# DEPARTMENT OF PARKS AND RECREATIONHRI # Trinomial CONTINUATION SHEET Property Name: ___ Hill Canyon Treatment Plant _____________________________________________________ Page 24 of 28demolished, expanded, or altered in subsequent plant expansions. Finally, Hill Canyon Treatment Plant does not possess high artistic value, and should not be considered representative of a significant and distinguishable entity whose components may lack individual distinction as the complex is comprised of ubiquitous and utilitarian structures and prefabricated industrial buildings. Consequently, the subject property is recommended not eligible under NRHP Criterion C or CRHR Criterion 3. Criterion D/4: That have yielded, or may be likely to yield, information important in prehistory or history. This report was limited to historical resources that are part of the built environment. NRHP Criterion D and CRHR Criterion 4 generally applies to archaeological resources but may apply to a built environment resource in instances where a resource may contain valuable information about such topics as construction techniques or human activity. Therefore, the built environment components of the subject property are recommended not eligible under NRHP Criterion D and CRHR Criterion 4. City of Thousand Oaks Significance Evaluation The Hill Canyon Treatment Plant does not meet any of the criteria for listing in As a City of Thousand Oaks Landmark or Point of Historical Interest. Though the property does contain buildings and structures constructed over 45 years ago, the property, as a whole does not (1)the property was originally constructed as part of the Conejo Valley Sanitation Company holdings and predates the , as demonstrated above in NRHP/CRHR Criteria A/1 and C/3; (2) Is not associated with heritage, and plays a mundane and ubiquitous role in the development of the city and greater urban community after its founding, as demonstrated above in NRHP/CRHR Criteria A/1; (3) Was not found to be associated with the lives of people important to the history of the City, as demonstrated above in NRHP/CRHR Criteria 2/B; (4) Does not have the potential to yield information important to the prehistory or history of the City, as demonstrated above in NRHP/CRHR Criteria 4/D; and (5) Lacks a distinctive, identifiable building typology or architectural style, readily identifiable to the period of construction, region, nor does it demonstrate a unique method of construction, exemplify the work of a master or possess high artistic value. For all of these reasons Hill Canyon Treatment Plant is not eligible as a local City of Thousand Oaks landmark. The City of Thousand Oaks criteria for Points of Historical Interest are predicated on the idea that (1) a property is no longer extant; (2) a property has been highly altered such that it cannot convey original workmanship or materials; or (3) is the site of a historical event with no distinguishing visual landmarks or characteristics. The Hill Canyon Treatment does not qualify as a local City of Thousand Oaks point of historical interest either. Integrity Discussion National Register Bulletin 15: How to Apply the National Register Criteria for Evaluation states that the integrity of a property is based upon the historical significance and character-significance is fully established the Hill Canyon

Appendix D Noise Modeling Results

Field Noise Measurement DataRecord: 1565Project NameHill CanyonProject #12767Observer(s)Date2023-01-20Meteorological ConditionsTemp (F)63Humidity % (R.H.)28.9WindLightWind Speed (MPH)2Wind DirectionNorth EastSkyClearInstrument and Calibrator InformationInstrument Name ListPiccolo #1897Instrument NamePiccolo #1897Instrument Name Lookup KeyPiccolo #1897ManufacturerSoft dB inc.ModelPiccoloSerial NumberP0222050202Calibration Date5/2/2022Calibrator Name(SB) LD CAL200Calibrator Name(SB) LD CAL200Calibrator Name Lookup Key(SB) LD CAL200Calibrator ManufacturerLarson DavisCalibrator ModelLD CAL200Calibrator Serial #19952GPS Assistance UsedNoPre-Test (dBA SPL)93.4Post-Test (dBA SPL)94WindscreenYesWeighting?A-WTDSlow/Fast?SlowANSI?YesMonitoringRecord #1Site IDST2Site Location Lat/Long34.211345, -118.924397Begin (Time)10:44:00End (Time)11:59:00Other Lx (Specify Metric)LPrimary Noise SourceCreek water runningOther Noise Sources (Background)Birds, Distant Aircraft, Distant Conversations / Yelling, Distant Traffic, Rustling LeavesOther Noise Sources Additional DescriptionMetal gate opening and closing, 10:56 conversationIs the same instrument and calibrator being usedas previously noted?YesAre the meteorological conditions the same aspreviously noted?YesPage 1/7 Source Info and Traffic CountsNumber of Lanes1Lane Width (feet)15Roadway Width (feet)15Roadway Width (m)4.6Distance to Roadway (feet)3Distance to Roadway (m)0.9Distance Measured to Centerline or Edge ofPavement?Edge of PavementRoadway TypeRoadEstimated Vehicle Speed (MPH)20Speeds Estimated by:Driving the PacePosted Speed Limit Sign (MPH)20Traffic CountsVehicle Count SummaryA 2, MT 0, HT 0, B 0, MC 0Select Method for Recording Count DurationEnter ManuallyCounting Both Directions?YesCount Duration (minutes)15Vehicle Count TallySelect Method for Vehicle CountsUse Counter (+/-)Number of Vehicles - Autos2Number of Vehicles - Medium Trucks0Number of Vehicles - Heavy Trucks0Number of Vehicles - Buses0Number of Vehicles - Motorcyles0Description / PhotosTerrainMixedSite PhotosPhotoComments / DescriptionST2 SouthSite PhotosPage 2/7 Photo
Comments / DescriptionST2 EastSite PhotosPhoto
Comments / DescriptionST2 WestPage 3/7
Site PhotosPhotoComments / DescriptionST2 NorthMonitoringRecord #2Site IDST1Site Location Lat/Long34.204109, -118.925468Begin (Time)11:36:00End (Time)11:51:00Other Lx (Specify Metric)LPrimary Noise SourceTrafficOther Noise Sources (Background)Birds, Distant Aircraft, Distant Traffic, Rustling LeavesOther Noise Sources Additional DescriptionFootstepsIs the same instrument and calibrator being usedas previously noted?YesAre the meteorological conditions the same aspreviously noted?YesSource Info and Traffic CountsNumber of Lanes4Lane Width (feet)10Roadway Width (feet)60Roadway Width (m)18.3Distance to Roadway (feet)3Distance to Roadway (m)0.9Distance Measured to Centerline or Edge ofPavement?Edge of PavementRoadway TypeBoulevardEstimated Vehicle Speed (MPH)50Speeds Estimated by:Driving the PacePosted Speed Limit Sign (MPH)45Page 4/7 Traffic CountsVehicle Count SummaryA 58, MT 2, HT 1, B 1, MC 0Select Method for Recording Count DurationEnter ManuallyCounting Both Directions?YesCount Duration (minutes)15Vehicle Count TallySelect Method for Vehicle CountsEnter ManuallyNumber of Vehicles - Autos58Number of Vehicles - Medium Trucks2Number of Vehicles - Heavy Trucks1Number of Vehicles - Buses1Number of Vehicles - Motorcyles0Description / PhotosTerrainMixedSite PhotosPhoto Comments / DescriptionST1 SouthwestSite PhotosPage 5/7
Photo
Comments / DescriptionST1 SoutheastSite PhotosPhoto
Comments / DescriptionST1 NorthwestPage 6/7
Site PhotosPhoto
Comments / DescriptionST1 Northeast

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Thousand Oaks City CouncilMarch 25, 2025

Thousand Oaks City Council
March 25, 2025