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SeattleCityLightEnvironmentReport20135ContributingtoScienceCityLightunderstandsthattheessenceofsoundscalenvironmentalmanagementliesintheabilitytoembracescience-baseddecision-making.TolicenseallitshydroelectricprojectsCityLightdevelopedasetofenvironmentalmeasuresthatwerebasedonsciencresearch.ResearchtoinformouroperaonsandgaugethesuccessofenvironmentalstewardshipaconsconnuesatourSkagitRiverBoundaryandToltprojectsinpartnershipwithstateandfederalagenciestribesandnonprotorganizaons.FishResearchUnderstandingthelifehistoriesandabundanceoftheshspeciesoccurringintheSkagitPendOreilleToltandCedarriversisanimportantpartofconrmingwhethermeasurestakenbyCityLighttoprotectshareeecve.ResultsofsomeofourrecentsheriesstudiesincludeToltRiverSteelheadAtaggingstudyofjuvenilesummersteelheadthatliveaboveacanyonalongtheToltRiverprovideddataonhowlongtheshstayabovethecanyonwhentheyleavetheiresmatedageandhowfasttheyaregrowing.ArecentgenecstudyconrmedthatthesummersteelheadpopulaonfoundabovetheToltCanyonisdierentfromthewintersteelheadpopulaonfoundbelowthecanyon.SkagitRiverBullTroutGenecsAcomprehensivebulltroutgenecsstudyfoundthatpopulaonsofthisspeciesareextremelydiverseintheSkagitRiverdrainagewithgenecallyuniquepopulaonsBulltroutandthisDollyVardenarespeciesofnativechartrout-likeshinthesalmonfamily.Inthesummerof2013thersttwoadultsteelheadtaggedin2010returnedtothesouthforkoftheToltRiverontheirwayupstreamtotheToltCanyon.CityLightisaleaderinsponsoringgeneticresearchstudiestoimprovethemanagementofthreatenedshspeciesinthePacicNorthwest.presentinalmosteverymajorstream.MostimportantthebulltroutpresentinthethreeSkagitreservoirsaregenecallyverydierentfromthosefounddownstreamoftheSkagitRiverProjectandhavelikelybeenisolatedfromtheshinthelowerwatershedsincetheendofthelasticeage.SkagitRiverSteelheadHatcheryandWildSteelheadInteraconsThisstudywasconductedtoassesswhetherhatcherysteelheadhaveharmfulecologicalandorgenecimpactsonwildsteelheadpopulaonsintheSkagitwatershed.Itfoundthat11to20percentofwildsteelheadexhibithatcherygenecmarkers.SkagitRiverProjectNaveCharPopulaonsThisstudyfoundthatbulltroutpopulaonshaveincreasedalmost10-foldintheRossLakedrainageoverthepastdecadealikelyresultfromamajorchangeintheforagebasefortheseshoverthisperiod.ThisstudyalsodiscoveredthatDollyVardenarepresentalongwithbulltroutinallthreeSkagitreservoirswhichmaybetheonlylakesintheUnitedStateswherebothoftheseshspeciesarefoundtogether.