CaseStudy:ConsolidatedIrrigationDistrictRechargeProgramConsolidatedIrrigationDistrict(CID)islocatedintheSanJoaquinValley,ontheeastern

sideofFresnoCounty,andincludessmallportionsofTulareandKingscounties.Figure1showstheboundariesofCID.IncorporatedcitieswithintheboundariesofCIDincludeFowler,Kingsburg,Parlier,Sanger,andSelma.OthersmallerurbanenclavesarefoundintheunincorporatedareasandincludeCaruthersandDelRey.CIDoverliestheKingsBasin,whichispartofthelargerTulareLakeBasin,asdefinedintheCaliforniaDepartmentofWaterResources(DWR)Bulletin118(DWR,2003).

Figure 1 – Consolidated I.D. Boundary 

 

CIDiscomprisedof145,000acres,themajorityofwhichisinagriculturalproduction.Cropwaterrequirementsaremetthroughirrigationapplicationofbothsurfaceandgroundwater.Surfacewaterdeliveredtoagriculturereducestherelianceongroundwater.Totalurbanwaterdemandsaremuchsmallerthanthetotalagriculturalwaterdemands,butthegrowingurbanizedareasarereliantexclusivelyongroundwater.

Consolidated I.D.

CIDwasorganizedonSeptember8,1921andhasbeenactivelymanaginglocalwatersuppliesthroughconjunctiveusesincetheagencywasformed.Conjunctiveuseisthecombinedmanagementofsurfacewaterandgroundwatersuppliesandstorage.TheDistrict’shistoricconjunctiveuseprogramincludesthediversion,inwetteryears,ofallocatedKingsRiverwaterandKingsRiverfloodreleasesintotheDistrict’sserviceareaforirrigationandgroundwaterrecharge.Partofthesurfacewaterappliedtoagriculture,thatisnotconsumedbythecrops,percolatesdownwardandrechargesthegroundwaterbasin.TheintentionaluseofsurfacewaterinlieuofgroundwaterpumpingispartoftheCIDconjunctiveuseoperations.Indrieryears,growersirrigatewithavailablesurfacewatersuppliessupplementedbypumpingofrechargedgroundwater.

CIDhaswaterrightstotheflowoftheKingsRiverandstoragerightsinPineFlatReservoir.SurfacewaterisstoredinPineFlatanddivertedbyCIDfromtheKingsRiverfordistributionthrough350milesofcanals.Figure2showsthecanalsystemwithinCID.

Figure 2 ‐ Consolidated I.D. Canal System 

ASanJoaquinValleypioneeringroundwatermanagement,CIDbeganitsrechargeprogram

byacquiringitsfirstpercolationbasinin1932.Aninitialplanofsixteenpondseventuallygrewtoincludeover50dedicatedrechargebasinswithasurfaceareaofapproximately1,300acres,locatedinthesandysoilsoftheKingsRiver’salluvialplain.Averagepondrechargeisapproximately30,000acre‐feet,rangingfromzerointhedirestofyears,toamaximumof187,000acre‐feet.ThesandysoilsintheCIDareamaketheirpondscapableofrechargingover1,200acre‐feetperday.Inaddition,seepagefromthebottomofthecanalsandditchesrechargesanother300acre‐feetperdaywhenfull.Figure3showsCIDrechargebasins.

Figure 3 – Consolidated I.D. Recharge Ponds

Duringthe2010‐2011wateryear,therewere168dayswhenfloodwaterwasavailable.StartingonDecember30,2010,CIDstarteddivertingfloodwaterfromtheKingsRiveruntilmostoftheirpondswerefull.CIDkeptthepondsfullwithaflowof750cubicfeetpersecond(CFS)tomaintainthewaterlevelsintheponds.Thisresultedin250,000acre‐feetofwaterbeingrechargedintothegroundwaterbasinduringthat168‐dayperiod.ThisvolumeofrechargeinoneyearresultedinraisingtheaveragewatertableelevationthroughoutCIDby7.06feet.

TheaverageannualsurfacewatersupplyforCIDisapproximately238,000acre‐feetbutcanvaryfromthelowof13,500acre‐feetin1976toahighof616,000acre‐feetin1967.WhileCIDiscomprisedof145,000acres,divertedwaterisusedforsurfaceirrigationonapproximately95,000acres.TheremainingareasofCID,includingthecitiesandunincorporatedcommunities,relyexclusivelyongroundwater.Figure4showshistoricsurfacewaterdiversionsandtheaverageddeclineinthewatertableunderlyingCID.

DespitetheactivemanagementofKingsRiverwaterbyCIDandtheotheroverlyingwaterdistricts,groundwateroverdraftisoccurringintheKingsBasinonanaverageannualbasis.Thismeansthat,whileinsomeyearsmorewaterisrechargedthanremovedandgroundwaterlevelsrise,onaverage,moregroundwaterisremovedthanisrecharged.Thisisevidencedby

Figure 4 ‐ Surface Water Diversions vs. Average Depth to Groundwater 

thelong‐termdeclineingroundwaterlevelsdepictedinFigure4.TheKingsBasinIntegratedGroundwaterandSurfaceWaterModel(KingsIGSM)wasusedtoevaluatetheregionalwaterbudgetandtoquantifyoverdraftforthemorerecentperiodof1964to2004.BasedontheKingsIGSM,theaverageannualoverdraftwithinCIDforthe40‐yearperiodwasapproximately24,000acre‐feet.TheentireKingsRiverBasinwasoverdraftedbyapproximately160,000acre‐feetperyearduringthesametimeperiod.

TheareatothewestofCIDisreliantexclusivelyongroundwater.Pumpinginthisarea

createsasteepgroundwatergradientfromeasttowest,resultinginthemovementofwaterfromCIDtowardsthetroughinthelowerpartoftheKingsBasin.Figure5showsthegeneraldirectionofgroundwaterflow.ThroughoutthecentralandwesternportionsofCID,thewestwardgradienthassteepenedandgroundwaterlevelshavedroppedasmuchas80to100feet.ThesteepenedgradientandthetrendfordecliningwaterlevelsarelikelytocontinueintothefutureifadditionalgroundwatermanagementstrategiesarenotimplementedwithintheKingsBasin.

Figure 5 – General Direction of Groundwater Flow