Wria 41 Lower Crab Creek 2006

WRIA 41 LOWERLOWER CRAB CREEK 2006 –— SSUMMARYUMMARY OF WWATERATER SSAMPLINGAMPLING FORFOR MMOSESOSES LLAKEAKE

MMARCHARCH 2007

Prepared forfor.: Moses Lake IrrigationIrrigation anandd RehabilitatRehabilitationion District 10531053 West Broadway Avenue PO BoBoxx 98 Moses LakeLake,, WashingtoWashington,n, 98837

M WATER M QUALITY M ENGINEERING

WRIA 41 LOWERLOWER CRAB CREEK 2006 —– SSUMMARYUMMARY OF WWATERATER SSAMPLINGAMPLING FORFOR MMOSESOSES LLAKEAKE

Prepared for:for: Moses Lake Irrigation and Rehabilitation District 1053 West BroadwBroadwayay Avenue PO Box 98 Moses Lake, Washington 98837

Prepared by: Water QualiQualityty Engineering, IncInc 103 Palouse Street, SuSuiteite 2 Wenatchee, Washington 98801

March 12, 22007007

M WATER M QUALITY M ENGINEERING

TABLE OF CONTENTS

1.0 INTRODUCTINTRODUCTIONION...... 9 2.0 MOSES LAKE AREA BACKGROUND...... 9 2.1 WWATERATER QQUALITYUALITY SSTATUSTATUS ...... 1010 3.0 MOSES LALAKEKE AAREAREA GEGEOLOGYOLOGY AND HHYDROGEOLOGYYDROGEOLOGY...... 12 3.1 GGEOLOGYEOLOGY OOFF THE MOMOSESSES LALAKEKE AREA...... 1212 3.2 HHYDROGEOLOGYYDROGEOLOGY ...... 1313 3.3 GGROUNDWATERROUNDWATER QUALIQUALITYTY ...... 1313 3.3.1 Natural CoConditionndition of PhospPhosphorushorus in AreaArea GrounGroundwaterdwater...... 1313 3.3.2 AnthropogenicAnthropogenic SourceSourcess of PhospPhosphorushorus ContriContributingbuting ttoo GrouGroundwaterndwater...... 1515 4.0 PURPOSE ANDAND GGOALSOALS...... 15 4.1 LLAKEAKE SAMPLING GOGOALSALS ...... 1515 4.2 GGROUNDWATERROUNDWATER SSAMPLINGAMPLING GOGOALSALS...... 1515 4.3 SSEPTICEPTIC SSYSTEMYSTEM EVALUATIONS ...... 1515 4.4 CCRABRAB CCREEKREEK SSAMPLINGAMPLING ...... 1616 5.0 SAMPLING METHODS AND SITES...... 16 5.1 QQUALITYUALITY CCONTROLONTROL FOFORR SAMSAMPLEPLE ANALYSISANALYSIS...... 1616 6.0 RESULTS AANDND DISCUSDISCUSSIONSION ...... 17 6.1 LLAKEAKE SSAMPLEAMPLE SSTATISTICSTATISTICS...... 1717 6.2 GGROUNDWATERROUNDWATER SSAMPLEAMPLE SSTATISTICSTATISTICS ...... 1717 6.3 LAKE SAMPLING ...... 1818 6.3.1 Lake SamSamplingpling...... 1818 6.3.2 Dilution Flows...... 1818 6.3.3 Lake WateWaterr QualityQuality - PhoPhosphorussphorus ...... 21 6.3.4 Lake WateWaterr QualityQuality— – Algae,Algae, ChloChlorophyll,rophyll, and VisibilVisibilityity ...... 21 6.3.5 Lake TroTrophiophic Status ...... 24 6.4 LLAKEAKE SSEDIMENTEDIMENT SAMPLING...... 25 6.5 CCRABRAB CCREEKREEK SSAMPLINGAMPLING ...... 25 7.0 GROGROUNDWATERUNDWATER ...... 30 7.1 PPHOSPHORUSHOSPHORUS IN MUNICIPAL WASTEWATER EFFLUENT...... 30 7.2 PHOSPHORUS ANALYZED FROM DOMESTIC AND OTHEOTHERR AREAAREA WELLS...... 33 7.3 SSODIUM,ODIUM, CCHLORIDE,HLORIDE, BBORON,ORON, PPH,H, AND TTEMPERATUREEMPERATURE...... 35 7.4 SSEPTICEPTIC SSYSTEMSYSTEMS IN THE REREGIONGION ...... 40 7.5 GGROUNDWATERROUNDWATER LOADS FRFROMOM WASTEWATER DISPOSAL...... 42 8.0 COCONCLUSIONSNCLUSIONS...... 4433 8.1 LLAKEAKE WWATERATER QQUALITYUALITY ...... 43 8.2 GGROUNDWATERROUNDWATER...... 43 9.0 RECORECOMMENDATIONSMMENDATIONS...... 43 10.0 REFEREREFERENCESNCES...... 4455 APPENDIX 0011 —– LALAKEKE SASAMPLEMPLE DATDATAA...... 47 APPENDIX 0022 –— LALARSONRSON WWTP EFFEFFLUENT,LUENT, WWWWTPTP MONITOMONITORINGRING WELLWELLS,S, AND GGROUNDROUND WAWATERTER DDATAATA FOFORR RESIDENTIRESIDENTIALAL MMONITORINGONITORING WELLS ...... 48 APPENDIX 03 —– SEDIMENT DATA ...... 49

WRIA 41 LoLowerwer Crab CCreekreek iiii M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING APPENDIX 04 —– CRAB CRCREEKEEK WAWATERTER DADATATA ...... 50 APPENDIX 5 -- ROROCKYCKY FFORDORD FLOFLOWW DATDATAA...... 51

TABLES Table 1.1. Physical Characteristic of Moses Lake (Bain 1990)1990) (based(based on water surface elevation of 10461046 ft).ft) ...... 1010 Table 2. External TP loloadad contributions to MoMosesses Lake (May through September) during critical loadload conditconditionsions and TP loads following 35% load reductions ((CarrollCarroll 2006)...... 1212 Table 3. Summary of QA|QAlQCQC Statistics (relat(relativeive percent diffedifference,rence, RPD) for the two sets of lakelake samsamples.ples...... 1177 Table 4. Summary of Average RPD for Larson Wastewater Effluent Samples...... 1717 Table 5. Summary of Average RPD for Larson Monitoring Wells...... 1818 Table 6. Summary of Average RPD for Domestic Wells.Wells ...... 1818 Table 7. Moses Lake Dilution Water Release Record...... 20 Table 8. Summary of lalakeke sampling during 2006...... 22 Table 9. Densities ooff algalgaeae in the lake in July anandd SeptembeSeptember.r...... 23 Table 10.10. Sediment sampling sites inin Laguna aandnd Wild Goose InletsInlets on 9/21/06...... 26 Table 11.11. Crab Creek sampling locations...... 27 Table 12.12. Crab Creek water quality results prior and during flow augmentaugmentationation study by USBR...... 28 Table 13.13. WWaterater quality from flood pond around dairy on Road 10.10...... 31 Table 14.14. Estimated monthly loads ttoo groundwater from the Larson WWTP inin 2006.2006 ...... 32 Table 15.15. InIndividualdividual Well Information ...... 33 Table 16.16. ConcentrationConcentrationss of phosphphosphorus,orus, chloridchloride,e, sodium, and boron inin Larson WWTP effluent...... 34 Table 17.17. 22006006 SummaSummaryry of GroundGroundwaterwater Parameters from WWTP momonitoringnitoring wells...... 34 Table 18.18. Summary of GroundwateGroundwaterr Parameters from Domestic Wells...... 36

FIGURES Figure 1.1. Moses Lake Watershed ...... 1111 Figure 2. Groundwater flow direction inin Moses LLakeake basin (a(arrows).rrows). Tan areas arouaroundnd lake are Pleistocene gravel and sand flood dedepositsposits (from Pitz 2003)...... 1414 Figure 3. Detail - VicinVicinityity Map of Cascade Valley and Lake Sampling Stations...... 1919 Figure 4. Detail VicinVicinityity Map of Pelican Horn and Lake Sampling Stations...... 1919 Figure 5. Comparison of Dilution flowflowss frfromom Rocky Coulee WWastewayasteway in 2005 and 2002006.6...... 21 Figure 6. Crab Creek floflowsws during USBR flow auaugmentationgmentation from Brooks Lake. Flow augmentation occurred ffromrom early August to December 15th15th 2006...... 29 Figure 7. Comparions of Rocky Ford flow during supplemental feed studstudyy (2006-2007) with previous flofloww records...... 29 Figure 8. Sampling sites on Rd 1010 Dairy during flow augmentaugmentationation study. ApproximatApproximatee flooded area is shoshownwn (map frofromm Google Earth)...... 30 Figure 9. WWellsells and GroGroundwaterundwater Sampling Locations...... 32 Figure 10.10. TTotalotal PhosphPhosphorusorus ConceConcentrationsntrations –— Domestic, WWTP MonMonitoringitoring wells, and Bain (2002) Wells.Wells ...... 37 Figure 11.11. Ortho-Phosphorus ConceConcentrationsntrations —– Domestic and WWTP Monitoring WWells.ells...... 37 Figure 12.12. Sodium Concentrations —– Domestic and WWTP monitor wells...... 38

WRIA 41 LoLowerwer Crab CCreekreek iiiiii M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING Figure 13.13. Chloride concentrations - Domestic and WWTP Monitoring wellswells...... 38 Figure 14.14. Boron Concentrations —– Domestic and WWTP Monitor Wells...... 39 Figure 15.15. ppHH Values - Domestic and WWTP Monitor Wells...... 39 Figure 16.16. Groundwater Temperatures - Domestic and WWTWWTPP Monitor Wells...... 40 Figure 17.17. Current and potential development of Cascade Valley using drdrainain fields for disposal of residentiaresidentiall wastewater...... 41

WRIA 41 LoLowerwer Crab CCreekreek iviv M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING SIGNATURE

Peter S. BuBurgoon,rgoon, Ph.D., PE Principal EnEnvironmentalvironmental Scientist

WRIA 41 LoLowerwer Crab CCreekreek v - WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING EXECUTIEXECUTIVEVE SUMSUMMARYMARY

InIn 2006 the sampling effeffortort was focufocusedsed on evaluating sources of phospphosphorushorus that may be entering Moses Lake. The disposal of wastewater to groundwater at the LaLarsonrson WasteWastewaterwater Treatment and from residential septsepticic systems waswas the primary source evaluated. ThTheseese were chosen as tthehe point of ffocusocus for 20020066 since they are known sources of rrelativelyelatively high loadsloads of phosphorus to the groungroundwaterdwater that if necessary can be contrcontrolledolled with available wastewaterwastewater treatment technology. The goal of tthehe effort was to estimatestimatee phosphoruphosphoruss loadsloads to ththee lake from these sources and compare them to loadload reductionsreductions recommendedrecommended inin the WashingtWashingtonon State Department of Ecology TMDL assessment.

The Larson Wastewater Treatment Plant is permitted to treat and dischardischargege a maximaximummum wastewater flow of 750,000 gagallonsllons per dadayy (gpd). In 2006 the average flow treated at the ffacilityacility was 324,000 gpdgpd.. The infiltrainfiltrationtion basinbasinss discharge ththee wastewater into coarse sandy and gravelly soils laidlaid dodownwn during glacial floodfloods.s. Wastewater has been discharged at this site sinsincece the 1970’s.1970’s. The wastewater isis dispodisposedsed intointo rapidrapid infinfiltrationsiltrations bbasinsasins that are locatedlocated one mile from western lakeshore and about 3 miles from southwestern lakeshore. ThThee groundwater flow is towards the lakelake inin a sosouthwesternuthwestern direction. DDuringuring the 20200606 sampling, concentrations of phosphorus inin the groungroundwaterdwater below the infiltrainfiltrationtion basinbasinss averaged 2079 ug/L TP. Total phosphorus (TP) concenconcentrationstrations inin wastewaterwastewater effluent averaged 2614 ugug/L./L. The 2020%% reduction inin TP coconcentrationncentration in the groundwater is duduee either to dilution from groundwater or removal inin the soil matrix.

RemoRemovalval of phosphorus inin the sandy gravels inin tthehe soil and aquifer is exexpectedpected to be low because 1)1) the sands and gravels are coarse and calcareous and 2) long ttermerm loadingloading to the site, more than 25 years, has probably exhausted the limitedlimited removalremoval capacity. Low remoremovalval implies that ththereere should bbee an identifiableidentifiable plume of wastewater mixed witwithh groundwater moving southwest frfromom the WWTP towards Moses LakeLake.. A network of documented wells was organ- izedized to help locatelocate a pluplume.me. The network was originally put together inin 22001001 and useusedd to develop a surficial groundgroundwaterwater model to evaluate TCE contamination inin ththee Cascade Valley. Un- fortunately regularregular acceaccessss to the wells is not perpermittedmitted due to a lawsuit ooverver the TCE contamination. The limitedlimited numbnumberer of wells tthathat were sampled in 2006 indicated that the phophosphorussphorus is not migrating into the babasaltsalt and is in the upper ppartart of the susurficialrficial aquaquiferifer where itit cacann discharge into Moses LakeLake..

A mamaximumximum loadload from the current WWWTPWTP can be estimated if itit isis aassumedssumed that there is no significant removal of TP between the wells and Moses Lake. InIn this scenscenario,ario, the estimated groundwater load for April through SSeptembereptember that may flow iintonto Moses Lake from the Larson WWTP was 601 kg. This load coucouldld reachreach the lalakeke in a coupcouplele of months to a couple of years depending oonn the groundwater seepage velocitievelocities.s.

Septic systesystemsms in the rapidly growing Cascade Valley area are predominantly installed in very gravelly (Type 1A)1A) soils. These soils are genergenerallyally calcareocalcareousus and coarcoarsese grained aandnd are not expected to remove signsignificantificant amouamountsnts of phospphosphorus.horus. Currently there are about 3,13,15656 acres of land available for residential development in the Cascade Valley. About 917 acreacress of that total has more than 490 dwelling unitunitss with septisepticc systems. The estimated loadload from existing septic systesystemsms to Moses Lake is 464666 kg TP. This estimate is based on aann “average” wastewater, 20-30% removalremoval inin tthehe septic tatank,nk, 20% reremovalmoval in the drain field, and 10%10% removal in the groundwater matrix. TheThesese assumptions could bbee strengthenstrengtheneded with more extensive field sampling. At this time, this is a ball parparkk estimate of the loads frofromm existing septic systems inin the

WRIA 41 LoLowerwer Crab CCreekreek 6 - WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING area. This is probably a low load estestimateimate since septic systesystemsms installed prior to 19919933 were not accounted fforor because ttheyhey were nonott inin the Grant County electronic datadatabase.base. IfIf the Cascade Valley is dedevelopedveloped to allowable dendensitiessities withoutwithout a sewer system, the loadsloads from septic systems and impactsimpacts to Moses Lake will be much greater.

Disposal of municipal aandnd residential wastewater appears ttoo be a very significant source of groundwater phosphorus entering Moses Lake. TThehe total estimated load in 2006 from the two sources is 11067067 kg TP over a six momonthnth period. The estimated load is 1142%42% of the recommended groundwater load reduction from the Moses Lake TTMDLMDL and ababoutout 32% of tthehe total loadload recommended by WA DOE for all of MoseMosess Lake. InInstallationstallation of pphosphorushosphorus rremovalemoval technology at the Larson WWastewaterastewater Facility, a sesewerwer collectiocollectionn system in Cascade Valley, and/or requirements for removaremovall of phosphophosphorusrus inin resideresidentialntial septsepticic systems will result inin a sigsignificantnificant loadload reductireductionon to Moses Lake. Implementation of methods to reduce phphosphorusosphorus loloadsads will im- prove the long term quality of Moses Lake.

InIn addition ttoo groundwater sampling, the lakelake wawass also sampled in July aandnd SeptembSeptemberer 2006. The dilution flow added to Moses Lake via Rocky Coulee WWastewaterastewater for the year was 194,800194,800 acre feet. EEighty-sixighty-six percent of the ddilutionilution flow was added before the eendnd of May. The relatively lowlow dilution flows inin July and August, the hhottestottest months of the summer, appears to have contributed ttoo lowlow lakelake water quality inin the latelate susummer.mmer. InIn September, the average surface water concentrconcentrationation inin the lakelake was 54 ug/L TP. ConcentrationConcentrationss were equal to or greatgreaterer than 60 ug/L in the lower portion of Rocky Ford Arm and inin the south end of the lake. These high concentrations supported lalargerge blooms of toxic blue green algae that concenconcentratedtrated inin the south end of the lake.

The concentconcentrationsrations of totoxicxic blue gregreenen algae were at levels considered ttoo be a moderate to high risk by the World Health Organization. When concconcentrationsentrations are this hhigh,igh, health districts or lakelake associaassociationstions are recommendedrecommended ttoo post signsigns,s, restrict aaccessccess to the lalake,ke, and make meas- urements of cyanotoxins to clarify coconcernsncerns abouaboutt toxicity. The primary cconcernsoncerns wowoulduld be for: residents ththatat have drinking water wells in hydrahydrauliculic contcontinuityinuity with the lake,lake, risksrisks to pets and livestocklivestock drinking the lalakeke water, and swimmers itchitch or rashrasheses to anyone swimming inin the lake.lake.

InIn August 22006006 the United States Bureau of Reclamation bbeganegan evaluation of the uusese of Crab Creek as a supplemental route for ffeedeed water to Potholes Reservoir. There were concerns that expected additional flow rates of 150150 cfs would ererodeode soil and transport lalargerge loads of sediment and nutrientnutrientss into ParkeParkerr Horn. Sample results from August through December reverevealedaled no significant changes in waterwater quality entering Parker Horn during the suppsupplementallemental flofloww study.

The entire supplemental feed flow from Brooks Lake was nnotot accounteaccountedd for inin surfasurfacece water flows at the Road 7 USGS flow gaggagee on Crab Creek. FlowsFlows in Crab Creek peaked in mid De- cember at about 95 cfs. This isis aboaboutut 75 cfs gregreaterater than expected base flows inin Crab Creek for this time of year. The significant chchangeange in the hydrograph in December implies that a new flow condition for Crab Creek was developing. IfIf susupplementalpplemental flows had cocontinuedntinued past December 1515 it appearappearss that a signsignificantificant perpercentage,centage, certainly greater than 50%, of the supplesupplementalmental flow would have entered Moses Lake via Crab Creek.

During the flow study a dairy on CraCrabb Creek was flooded. ThThee resultant ppondond that forformedmed had up to 500 ppppbb TP. The land had beebeenn used for lalandnd applicatapplicationion of dairy wastewater. IfIfthis this pond had breached a nanaturaltural dike anandd reconnectreconnecteded to the main channel ooff Crab CreeCreekk the phosphorus loadload would have been significantsignificant..

WRIA 41 LoLowerwer Crab CCreekreek 7 - WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING All the supplemental feed flow was expected to flflowow into Moses Lake, if nnotot by Crab Creek, then via alternative subterranean routes. Rocky FordFord Creek flows increased significantly dduringuring the test period.

Future work for 2007 shoshoulduld focus on developmedevelopmentnt of a WateWaterr Pollution Control Plan fforor control of phosphorphosphorusus loads intintoo Moses Lake. This areareaa isis growing rapidlyrapidly with no control of phosphorus loads intintoo the lakelake frfromom municipal, residentresidential,ial, or agricultural wastewater disposadisposal.l. The lakelake will become more eutrophic if a pplanninglanning and actactionion strategy is not develdevelopedoped and implemented. This study makes it cleclearar that there isis a high rriskisk of phosphphosphorusorus loading from the disposal of wastewater at the LarsoLarsonn treatment Plant and from unsewered areas araroundound the lake. The City should be eencouragedncouraged ttoo begin planplanningning for a phphosphorusosphorus reremovalmoval systesystemm at Larson WWTP. The County and City should begin planning for either 1)1) A collection systesystemm inin the Cascade Val- leyley and other unsewered areas or 2) Requiring phosphorus rremovalemoval systsystemsems for residential septic systems inin the CascaCascadede Valley. IfIf these actactionsions are taketakenn about one third or more of the total TP loaloadd reductionreduction rrecommendedecommended by DepartDepartmentment of Ecology’s TMDL assessmenassessmentt could be achieved. More importantly, the long term recrrecreationaleational benbenefitsefits of Moses Lake will be protected and/or enhanced.

WRIA 41 LoLowerwer Crab CCreekreek 8 - WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

1.01.0 INTRODUCTION

InIn 2006 the Moss Lake IrrigationIrrigation and Rehabilitation District (MLIRD) ccontractedontracted with Water Quality Engineering to start a phospphosphorushorus asseassessmentssment for Moses Lake. A source assessment was recommended for the following reasons:reasons:

1.1. 2005 lake water sampling showed elevated pphosphorushosphorus concentratioconcentrationsns (>50 ppppb)b) in several localocationstions around the lake.lake. 2. ItIt was agreed that water pollution cocontrolntrol planninplanningg would be beneficial foforr the lake due to concerns ababoutout municipmunicipal,al, residential,residential, and agragriculturalicultural wastwastewaterewater pollupollutiontion inin the MMosesoses Lake drainadrainagege basin. 3. DevelopmeDevelopmentnt of a water pollution cocontrolntrol plan cacann be completed and be approved by WA DOE as an alternative to the Total MaxiMaximummum Daily Load (TMDL) proceprocess.ss. 4. The assessment would serve as a foundation foforr a water pollution controcontroll plan 5. A water pollution controcontroll plan can bbee approved as an aalternativelternative to the Total Maximum Daily Load (TMDL) procprocess.ess.

2.0 MOSES LAKELAKE AREA BACKGROUND

Moses Lake isis a shallow warm water lakelake covering an area of approximately 6800 acres (10.6 square miles). TThehe watershed to Moses Lake encompasses apprapproximatelyoximately 2,2,450450 square miles, principally within the Crab Creek drainagdrainage.e. The lakelake and adjaadjacentcent watershewatershedd lands are shown on Figure 1.1. Physical charactcharacteristicseristics of Moses Lake aarere provided in Table 1.1.

The City of Moses Lake and adjaceadjacentnt urban areas occupy much of the southeastersoutheasternn shoreline includingincluding arareaseas within ththee lake knowknownn as Parker Horn and Pelican Horn. Crab CreeCreekk waters enter the lakelake at the upper end of Parker Horn; USBR dilution water releases from the East Low Canal enter Crab Creek via Rocky Coulee WasteWastewayway approxiapproximatelymately one mile north of Parker Horn. A portion of the diluted water within Parker Horn is pumped across a narrow peninsula to Pelican Horn in order to dilute nutrienutrientsnts and improveimprove locallocal water quality. InIn years past the City of Moses Lake sewage effluent dischardischargedged into Pelican Horn. This major sosourceurce of nutrients was removed in 19791979 when sewage was transferred to a new treatment plant with efflueneffluentt disposadisposall to landslands east of Moses Lake.

The northern or main arm of Moses Lake is fed by a small spring fed tributary known as Rocky Ford Creek. SeSeee upper left hand corner of Figure 1.1. InIn 19871987 a small dam was con- structed at tthehe lower enendd of Rocky Ford Creek as part of ththee Moses LaLakeke Clean LaLakeke Project. This dam was designed to prevent upstream mimigrationgration of carp into the creek system as part of a program to enhance water quality within the crecreekek and Moses Lake. High phosphorus concentrations are associatassociateded with the Rocky ForkFork CreCreekek system and were aggravated by ccarparp activity within the crcreek.eek. The carp barrier provided a detention popondnd and made subsequesubsequentnt rehabilitation of the crcreekeek feasiblefeasible.. Carp had eroded the banks and uuprootedprooted vegetation within the creek. Carp remairemainingning inin the Creek were eradicated by the DepaDepartmentrtment of WiWildlifeldlife and a trout fishery was established. During 19961996 stop logslogs were reremovedmoved by vandals who compromised the strustruc-c- tures water quality control features by lowering the detention pond watwaterer surface and allowing carp to migrate upstreaupstreamm into Rocky Ford CreeCreek.k. The State DepartmeDepartmentnt of Fisheries and WildWild-- lifelife repaired the structure and rehabilitatedrehabilitated Rocky Ford Creek during 1998.1998.

WRIA 41 LoLowerwer Crab CCreekreek 9 - WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Table 1. PhPhysicalysical CharCharacteristicacteristic ooff MMosesoses LaLakeke (Bain 1991990)0) (based on wwaterater sursurfaceface eelevationlevation of 1046 ft). Moses Lake Surface Area 6,800 acres MaxiMaximummum Depth 38 feet Mean DeptDepthh 18.518.5 feet Volume 126,000126,000 acracre-feete-feet Total LengtLengthh 20.5 miles

Parker Horn Mean depth 12.612.6 feet Area 758 acres Volume 9,520 acre-facre-feeteet

Pelican Horn Mean DeptDepthh 15.615.6 feet Area 1,6001,600 acres Volume 25,000 acreacre-feet-feet

The Moses Lake Clean Lake Project also focused on nitrogen sources, particularly the deep percolpercolationation of nitrates from irrigationirrigation of agricultural lalandsnds within Blocks 40 aandnd 41 of the USBR Columbia Basin Project. TThehe project provided on-farm assistassistanceance to lolocalcal irrigators which incluincludedded cost shshareare assistaassistancence for irrigirrigationation systesystemm upgrades and for irrigationirrigation water managemenmanagementt programs. These major on-farm acactivitiestivities resultresulteded in fundinfundingg of improveimprovementsments on 36 farms and directly involved 5,35,34646 cropland acres. SuSubsequentbsequent prprojectoject spspin-offsin-offs occurred benefiting aapproximatelypproximately 7350 cropland acres bbyy the 19891989 irrigationirrigation seaseason.son. NutrieNutrientnt loss sav- ingsings and overall benefitbenefitss of the CleCleanan Lake Program were summarized inin a March 19901990 FinaFinall Report (Bain 1998).1998). Since completcompletionion of the CCleanlean Lakes Project, lake and surrosurroundingunding well have been monitored oonn a 5 year ccycleycle to provprovideide a historical data base and records on water quality in ththee lake since completion of the Clean Lakes projeproject.ct.

2.1 WATER QUALITY SSTATUSTATUS

Moses Lake isis claclassifiedssified as a Lake class under Washington State water quality stanstandardsdards (Chapter 173-210A173-210A WAC). Rocky Ford Creek isis classified aass Class A, aandnd Crab CreCreekek as Class B. Lake claclassss and Class A waters are required ttoo meet or exceed the reqrequirementsuirements for all or substantiasubstantiallylly all, of the fofollowingllowing charcharacteristicacteristic uses: domestic, industrial, and agricultagriculturalural water supply, stock watering; salmonid and other fish migration, rearing, spawspawning,ning, and haharvesting;rvesting; wildlife habithabitat;at; recreatiorecreationn (primary ccontactontact recrerecreation,ation, sport ffishing,ishing, boatboating,ing, and aestaesthetichetic en- joyment); anandd commerce and navigation. Class B water are required to meet or excexceedeed the requirements for most of the preceding uses (Carroll 2006).

WRIA 41 LoLowerwer Crab CCreekreek 10 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Figure 1. MoMosesses LakLakee WatershedWatershed

'miiM'm'i AIR FOR”. BASE] ““31“?”

" T 1%“... _ ‘s__:

U 0.5 1 2Miles ‘3' 5: l

Despite all tthehe work and benefits of tthehe Clean Lakes Project ((BainBain 1990)1990) Washington State De- partment of Ecology placed Moses Lake, Rocky Ford,Ford, and Crab Creek on the 2004 3303(d).03(d). The Lake was listed with a Category 5 listing for Total phosphorus. The lake ooutletutlet was also placed on the 303(d) for pH based on samples collectecollectedd from 19931993 —– 2001. InIn addition to tthehe water quality listings the lake was listed for elevated cconcentrationsoncentrations of 2,3,7,8 TCDD and PCBs in fish tissue (WA DOE 2005). Crab Creek was listedlisted for high pH and temperature at several loca-locations (mouth to Moses Lake, at USGS gage station, Road 1616 crossing) ((WAWA DOE 2005).

WRIA 41 LoLowerwer Crab CCreekreek 11 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Washington State Department of Ecology published the resuresultslts of ititss 20020011 water quality assessment with recommerecommendationsndations for reducingreducing phphosphorusosphorus loloadsads to Moses Lake (Carroll 2006). Final load rereductionduction recorecommendationsmmendations for bringinbringingg Moses Lake intointo comcompliancepliance with water qual- ityity goals are shown inin TTableable 2. The water qualitqualityy goal is thathatt Moses Lake will have an average concentratioconcentrationn of 50 ug/L Total PhospPhosphorus.horus. This standard apappliesplies from May through Septem- ber. The hydraulic condconditionsitions for the criticacriticall flow conditions aarere 9090thth percentile inflowinflowss from Rocky Ford Creek and Crab Creek and a 1010thth percentile flofloww or feed water through Rocky Cou- leelee Wasteway )based)based on flow recordsrecords from 1977-2001).1977-2001).

DevelopmeDevelopmentnt of a Total MaxiMaximummum Daily Load (TMDL) and rereductionduction stratstrategyegy was initiated with public hearings in 2002 but was discontinued in 2003. The TMDL proceprocessss for the lalakeke may be reconsiderereconsideredd inin 2007 ((PeelerPeeler 20042004).).

Table 2. ExteExternalrnal TP load contribucontributionstions to MoseMosess LLakeake (M(Mayay thrthroughough SepteSeptember)mber) durinduringg critical loadload conditiconditionsons and TP loads follofollowingwing 3535%% loadload reducreductionstions (Carroll 2002006).6). External Source TP load, TP load after 35% TP Load reduction External Source kg reduction(kgreduction(kg)) (kg) Crab Creek 17651765 11471147 591 Rocky Coulee Wasteway 687 447 240 GroundwateGroundwaterr 22150150 11398398 775252 Columbia Basin HatcheHatchery1ry1 7777 5500 2222 Columbia Basin HatcheHatcheryry Spring 15821582 10281028 554 Troutlodge HatcheriesHatcheries11 339898 225959 113939 Rocky Ford Creek 3089 2008 10811081 TTOTALOTAL 33379379 11HatcheriesHatcheries contributioncontributionss based on 2001 production levels.

3.0 MOSES LAKELAKE AREA GEOLOGY AND HYDROGEOLOGY

3.1 GEOLOGY OF THE MOSES LAKE AREA

The subsurfsubsurfaceace stratigrastratigraphyphy of the Moses Lake aarearea consists of a series of thick Miocene-age basalt lava flows and intinterbeddederbedded sesedimentsdiments is known as the Columbia River Basalt Group (CRBG). ThThee most recent basalts uunderlyingnderlying most of the Moses Lake aarearea are Roza Member ooff the Wanapum Basalt formation of the CRBG.

Throughout much of the area, the babasaltssalts are ovoverlainerlain by finfiner-graineder-grained deposits knoknownwn as the Ringold Formation. Ringold sediments in the Moses Lake aarearea are composed of lacustrine clay, silt, and ffineine sand. These sediments are thicker ttoo the west and pinch out east of the lakelake approximately one mile west of Crab Creek. PreviPreviousous research indicatesindicates ththee Ringold sesedimentsdiments separate Moses Lake frofromm the underlying basalt units for much of the areareaa between the airport and the city.

OverlOverlyingying the Ringold sesedimentsdiments are a sequence of PleistocePleistocene-agene-age flood deposits ththatat sur- round the majority of the lake. These flood deposits, known aass the Hanford Formation,Formation, consist of large,large, well-stratified boulder to granule-sized babasalticsaltic gravel with some deposits of sand, silt, and non-basalt gravel.

WRIA 41 LoLowerwer Crab CCreekreek 12 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

3.2 HYDROGEOLOGY

The finer-grained deposits of the RinRingoldgold Formation act as an aquitard, seseparatingparating grogroundwaterundwater inin the Hanford flood depdepositsosits from grgroundwateroundwater inin the underlying basalt units. This ppositionosition and distribution of the Ringold sedimentsedimentss with resperespectct to the lalakeke bed indicaindicatete that the majority of groundwater interacting with Moses Lake moves through the coarse grained Hanford flood deposits with limited interaction from the basalt unitunits.s. Groundwater moving intointo the lakelake along the southeastersoutheasternn shore of Pelican Horn and in the arareaea of the big bend may bbee transportetransportedd through the Ringold deposits (Pit(Pitzz 2003).

The Hanford Formation flood depositdepositss are highly permeable and can allow rapid groungroundwaterdwater movemovement.ment. Reported hydraulic condconductivitiesuctivities in tthishis formation rangerange from 2,800 to 28,000 ft/day. InIn addition, becabecauseuse of the coarse naturnaturee of these ddeposits,eposits, infiltinfiltrationration rates tthroughhrough the vadose zone are considconsideredered to be qquiteuite rapid with littlelittle attenattenuationuation capacapacitycity for pollupollutantstants (Pitz, 2003; MWH, 2003). Hanford Formation flood deposits are highly perme- Moses Lake has been ddescribedescribed aass a regional discharge fea- able and cacann allow rapid ture for shallow groundwater within tthehe Columbia Basin. groundwater movemovement.ment. GroundwateGroundwaterr elevation data inin the Hanford and Ringold deposits justjust eeastast of the lalakeke indicaindicatete tthehe main direction of groundwater flow in this area is in a south to sousouthwestthwest direction, with grgroundwateroundwater discharging to the lake aalonglong the eastern shorelinshorelinee (Figure 2). GroundwatGroundwaterer discharge volumes to the lakelake from the lowerlower permeability Ringold deposits iiss lilimitedmited but sisignificantgnificant (Pit(Pitz,z, 2003; MWH, 2001).

Recharge for both the uunconsolidatednconsolidated aquifers and tthehe basalt aquifer isis primarily from irrigation.irrigation. Primary creeks entering Moses Lake, Rocky Ford Creek and Crab CreeCreekk are both groundwater discharge arareas.eas. The recharge to the Rocky FordFord stream area comes from the nortnorthwesthwest (Eph- rata), and north (Soap Lake), and the northeast (Adrian). Recharge to the portion of Crab Creek between Adrian and Moses Lake isis primarily from the east and northeanortheast.st. Direct ggroundwaterroundwater recharge to Moses Lake isis from both east and west (Figure 2).

3.3 GROUNDWATER QUALITY

A historical median TP concentratioconcentrationn of 20 ug/ug L has3 been rereportedported from wells sampled between 19421942 and 19199292 in the cecentralntral Columbia PlateauPlatea (Pitz,itz, 2003)2003).. These data showed no clear trend inin TP conceconcentrationntration with depth as might be expected from a buried geologeologicgic sourcesource.. Reported TP concentrconcentrationsations averaged 35 ug/L as P in grougroundwaterndwater from wells less than 150150 fefeetet in the Moses Lake area since 19801980 (Pitz 22003).003).

3.3.1 Natural CoConditionndition of Phosphorus in Area GroGroundwaterundwater

The existence of surface or subsurfsubsurfaceace geolgeologicogic depositdepositss containing phphosphateosphate minerals were suggested ttoo cause the elevated phosphorus coconcentrationsncentrations in the groungroundwaterdwater in the Moses Lake area. Detailed mineralogical ddescriptionsescriptions of the Hanford and Ringold Formations are lim- itedited inin the litliteratureerature but there are no references ttoo the presenpresencece of signsignificantificant phosphaphosphatete mineral deposits inin tthesehese formations in published geologic rreportseports of tthehe area. InIn addition, the sediments of the Ringold FormationFormation underlying Moses Lake are thought to originate from granitic and vol- canic regionregionss located nonortheastrtheast of ththee Columbia basin. Such sediments aarere not likely to be a significant source of phophosphorus-richsphorus-rich sediments.

WRIA 41 LoLowerwer Crab CCreekreek 13 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

t I {i I C-eolagi: Saleem; Stanza: EXEC-EL JEE'S I f. after (milk. l'JSIII. "- T ’ _ -."-II:-_

Figure 2. GrGroundwateroundwater flofloww dirdirectionection inin Moses LaLakeke basin (arr(arrows).ows). Tan arareaseas arouaroundnd lake are PleistocenPleistocenee gravgravelel and ssandand flood dedepositsposits (from Pitz 2002003).3).

The slightly higher OP concentrationconcentrationss in the Moses Lake areareaa (35 ug/L) compared to the central Columbia Plateau (20 ug/L) may popossiblyssibly be duduee to a naturnaturalal mineral contribution; however prepre-- vious research suggestsuggestss human impimpactsacts ((Pitz,Pitz, 22003).003).

Rocky Ford Creek presents an anomaly to the presumed groundwater phosphorus lelevelsvels of 35 ug/L. Rocky Ford Creek is fed by a spring that historically has elevated levels of phosphorus. Carroll (2006) reported an average concentratioconcentrationn of 91 ug/L TP in the spspringring water. Pitz (2003) and Bain (2002, 1997,1997, 22002)002) speculate that the spring is ffeded with shalloshalloww groundwagroundwaterter originat- inging from the flood deposits northeast of the springsprings.s. Using trilinear analysis of water samples and historical geological evaluations, reasoned tthathat the sprinspringg water was not connectconnecteded to Soap Lake (a lake north of the springs which has phosphorus concentrations aass high as 63630000 ug/L TP).

Bain (1987) determined that phosphophosphorusrus may origoriginateinate from Brook Lake aandnd Round Lake. Nu- trients inin thethesese lakes apapparentlyparently originate from agricultural aactivitiesctivities inin ththee upper Crab Creek Basin and uupperpper Grant and Lincoln Counties. Bain found no available evidence for a natural stratigraphic source of pphosphorushosphorus tthathat could explain the eleelevatedvated concentrations prepresentsent in the groundwater. Pitz (200(2003)3) speculatespeculatess that the sosourceurce may be lowlow density rural development

WRIA 41 LoLowerwer Crab CCreekreek 14 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

combined with agriculturagriculturalal practicepractices.s. However, tthehe phosphorphosphorusus load from Rocky Ford Creek (Table 2) is equivalent to the amount that may produced by a population of about 60060000 people discharging wastewater directly into the Creek (assuming 80 gallons wastwastewater/person/dayewater/person/day with 6 mg/L TP). This lalargerge of a community isis difficult to ffindind between MoMosesses Lake anandd Spo- kane.

3.3.2 AnthropogAnthropogenicenic Sources of Phosphorus CoContributingntributing to Groundwater

Common sources of phophosphorussphorus in ggroundwaterroundwater are disposal of municipamunicipal,l, residential,residential, and agricultural wastwastewater.ewater. The focus of the 2006 source evaluation isis municipal and residenresidentialtial wastewater disposal inin tthehe Cascade Valley area. This area and sources were given high prior- ityity for evaluation becaubecausese many circumstances imimplyply that they mamayy be significant source of groundwater phosphorus. These circircumstancescumstances are: the hydrogeology, gravelly soils, the rapidrapid increaseincrease inin developmendevelopment,t, the close proximity to tthehe lake, anandd the long tetermrm disposal of wastewater inin to the area.

4.0 PURPOSE AND GOALS

This sampling program is the initiation of effoeffortsrts to develop a Water PolluPollutiontion Control Plan for Moses LakeLake.. The goal ooff the Plan will be to bettebetterr identify sosourcesurces and iimplementmplement programs to reduce loadloadss of phosphphosphorusorus into Moses Lake. TThehe assessment entails sampling groundwater, the lake, evaluating sepseptictic systems, and monitomonitoringring creeks fflowinglowing into Moses LakeLake.. General goals for 20200606 sampling are discudiscussedssed below.

4.1 LAKE SSAMPLINGAMPLING GOALS

Lake sampling in 2006 was done to monitor lake water quality following a wet winter. The USBR does not normally run a lot of water through the lake afafterter a wet yeyear.ar. The low dilution flows were expected to have negative impactsimpacts oonn lake water quality.

4.2 GROUNDWATER SAMPLING GOALS

Wastewater disposal frofromm the Larson WastewatWastewaterer Treatment Plant (WWTP) and septic systems be a source of groundwater phosphophosphorusrus that enteentersrs Moses LaLake.ke. The objectives of 22006006 sampling are to determine if there is:

1.1. Elevated concentration of phosphorphosphorusus in groundgroundwaterwater at momonitoringnitoring wells surroundinsurroundingg the Larson WWTP disposal area, 2. A groundwater gradient towards MoMosesses Lake or Crab Creek and, 3. A significasignificantnt phosphorus loadload to Moses Lake frofromm the wastewater dispodisposalsal site.

4.3 SEPTIC SYSTEM EVALUATIONS

This task involves evaluation of the current statstatusus of septic systems in the Moses Lake area. The objectivobjectivee of the task isis to quantifquantifyy the existing and future status of sesepticptic systems around the Lake.

WRIA 41 LoLowerwer Crab CCreekreek 15 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

4.4 CRAB CREEK SSAMPLINGAMPLING

The ColumbColumbiaia River Water Management PrograProgramm isis evaluating alternative methods to develop new water supplies for tthehe Columbia River basin. One of the alternative methods is to move water from Brooks Lake down Crab Creek and intointo Potholes Reservoir (WA DOE 2006). An early implementation study was started by UnUnitedited States Bureau of Reclamation inin August 2006. A sasamplingmpling program was established in 2006 to monitor impacts of additional flows in Crab Creek.

5.0 SAMSAMPLINGPLING MMETHODSETHODS AND SISITESTES

Phosphorus is reported as either Total Phosphorus (TP) whiwhichch includeincludess organic and inorganicinorganic phosphorus; or the solusolubleble form refreferrederred to as ortho-phosportho-phosphorushorus (OP) which is the form that is most available for biolobiologicalgical growthgrowth.. All phosphphosphorusorus data is reported in tthehe units of uug/Lg/L or parts per billion (p(ppb).pb). The TMDL target for phosphorus is 50 ppb TTP.P.

A Quality AsAssurancesurance ProProjectject Plan wawass developed for lake sasamplingmpling in 2005 (MLIRD 2005). Sites and prprotocolotocol were selected to assure conconsistencysistency with the Moses Lake PhosphPhosphorusorus TMDL Study QAPP (Carroll and Cusimano 2001). The QAPP wawass amended in 2006 to include groundwater sampling from area welwells.ls. Some of the Groundwater ManaManagementgement Association (GWMA) sampling procedures were adapted to provide continuity with the tri-county regional sampling program develdevelopedoped by GWGWMA.MA. InIn some cases the procedures adapted for the QAPP are the same or similar. Since phosphorus isis ththee item of primary concern in these eevaluationsvaluations procedures were modified where more exact sampling techtechniquesniques are rrequiredequired for phosphorus. The GWMA QAPP has bbeeneen approved by the United States Department of EnvironmeEnvironmentalntal Pro- tection (US(US EPA).

5.1 QUALITY CONTROCONTROLL FOR SAMPLE ANALYSISANALYSIS

Sample quality control measures were implementimplementeded in the field and the lalaboratory.boratory. One replicate sample was collectcollecteded in the field and analyzed for all wwaterater quality parameters. A duplicate sample was randomly seselectedlected inin the laboratorylaboratory and analyzed for each set of monthly samples. A spike samsample,ple, blank aandnd known ststandardandard were also analyzed in the lab for one randomrandom sample for each set of monthly samples.

Differences between the replicatereplicates,s, duplicateduplicates,s, and known standards wwereere compared using relative percent difference (RPD). Relative percent difference is calculatcalculateded by the equation below:low:

RPD = absoabsolutelute value of: [(X[(x11 - XxR)/(x1R)/(X1 + XXR)/2)],R)/2)],

XX11 isis the valvalueue of sample and XXRR the value of the parameter for the replicate or duplicate of XX1.1. The RPD gigivesves an understanding of the samplinsamplingg error from variability in the field and during laboratorylaboratory analysis.

WRIA 41 LoLowerwer Crab CCreekreek 16 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

6.0 RESULTS AND DISCUSSIDISCUSSIONON

6.1 LAKE SAMPLE STATISTICS

The RPD for each set of lakelake samplesampless is presepresentednted in Table 3. All data rreportedeported by Soil Test Consultants, IncInc are available inin AppAppendixendix 1.1. During analysis of the July samples the RPD of 10%10% was exceeded for oorthortho P during analysis of the known standard anandd for Total N during analysis of tthehe sample spike. These two exceedances also rresultedesulted in ththee average laboratory RPD being greater than the 10%10% target. During September tthehe average RPD for the laboratorylaboratory analysis were all less thathann the 10%10% ttargetarget (Table 3).

Table 3. SummarSummaryy of QA|QQAIQCC StaStatisticstistics (rela(relativetive ppercentercent differdifference,ence, RPRPD)D) for the ttwowo ssetsets ooff lakelake samples. OOrthortho P TTotalotal P TTotalotal N ppHH July Sample Lab DDuplicateuplicate 4% 8% 0% FFMM SamSampleple sspikepike 66%% 33%% 79% FM Known sstandardtandard 29% 3% 2% FFMM AverageAverage RPD 13% 5% 27% FM SSeptembereptember SSampleample Lab DDuplicateuplicate 0% 1414%% 0% 33%% SamSampleple sspikepike 33%% 33%% 00%% nnaa Known sstandardtandard 00%% 33%% 00%% 11%% AverageAverage RPD 11%% 66%% 00%% 22%% FFMM = FFieldield mmeasurementeasurement

6.2 GROUNDWATER SSAMPLEAMPLE STSTATISTICSATISTICS

The average RPD summaries for groundwater samples are presented in Tables 4 tthroughhrough 6. These incluincludede samples collected frofromm wastewatwastewaterer effluent aandnd monitoring wells at ththee

Table 4. SummarSummaryy of AverageAverage RPD for Larson WasteWastewaterwater Effluent SamplSamples.es.

Date Total P OrthOrthoo P SodiuSodiumm ChloriChloridede Boron 77/19/2006/19/2006 44%% 66%% 33%% 22%% 55%% 77/26/2006/26/2006 44%% 1313%% 33%% 99%% 55%% 88/2/2006/2/2006 44%% 11%% 33%% 33%% 33%% 88/9/2006/9/2006 44%% 11%% 33%% 33%% 33%% 88/16/2006/16/2006 55%% 22%% 11%% 11%% 44%% 88/23/2006/23/2006 55%% 11%% 11%% 11%% 44%% 88/30/2006/30/2006 33%% 22%% 22%% 22%% 44%% 99/6/2006/6/2006 33%% 11%% 22%% 22%% 44%% 99/13/2006/13/2006 66%% 22%% 22%% 00%% 44%% 99/20/2006/20/2006 66%% 2525%% 22%% 00%% 44%% 99/27/2006/27/2006 44%% 11%% 22%% 33%% 44%% 110/4/20060/4/2006 33%% 11%% 11%% 22%% 55%% 10/11/200610/11/2006 1212%% 99%% 11%% 11%% 55%% 110/18/20060/18/2006 55%% 22%% 11%% 11%% 44%% 111/8/20061/8/2006 11%% 22%% 22%% 11%% 44%%

WRIA 41 LoLowerwer Crab CCreekreek 17 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING

I 112/6/20062/6/2006 I 33%% I 11%% I 22%% I 11%% I 44%% I

Larson Wastewater Treatment Plant and those collected frofromm domestic private wells.

Appendix 2 contains the groundwater summary statistics for tthehe remaining parameters (lab duplicate, sample spikespike,, aandnd known ststandard)andard) and all data repreportedorted by Soil Test ConsuConsultants.ltants. The average laboratory RPD was less ththanan the 10%10% target for ththee majority of sampling ddatesates and groundwater constituentconstituents.s.

Table 5. SummarSummaryy of AverageAverage RPD for Larson MMonitoringonitoring Wells.Wells. Date Total P OrthOrthoo P SodiuSodiumm ChloriChloridede Boron 66/13/2006/13/2006 nnaa nnaa nnaa nnaa nnaa 77/11/2006/11/2006 nnaa nnaa nnaa nnaa nnaa 88/8/2006/8/2006 nnaa nnaa nnaa nnaa nnaa 99/12/2006/12/2006 66%% 22%% 22%% 22%% 33%% 110/10/20060/10/2006 33%% 22%% 11%% 11%% 55%% 111/7/20061/7/2006 66%% 11%% 33%% 55%% 33%% 112/5/20062/5/2006 33%% 33%% 22%% 11%% 44%% na - not available

Table 6. SummarSummaryy of AverageAverage RPD for DomesDomestictic WellsWells..

Date Total P OrthOrthoo P SodiuSodiumm ChloriChloridede Boron 110/30/20060/30/2006 66%% nnss 33%% 1010%% 3% 112/5/20062/5/2006 33%% 33%% 22%% 11%% 44%% 112/21/20062/21/2006 22%% 1414%% 33%% 44%% 77%% ns - not sampled

6.3 LAKE SSAMPLINGAMPLING

The 2005/22005/2006006 winter was very wewett and coconsequentlynsequently dilutdilutionion flows frofromm Rocky CoCouleeulee Waste- water were expected to be very low in 2006. Since the critical season fforor the TMDL isis for lowlow flow years tthehe plans were to sample the lake during this critical time. However, the flows from USBR to RoRockycky Coulee Wasteway were relatively normal so samples were only collected twice.

6.3.1 Lake Sampling

Lake sampling sites are shown in Figures 3 and 4. These sites are consistent with ththee 2001 TMDL lake assessment and other historic sampling recordsrecords ((MLIRDMLIRD 2002005)5)

6.3.2 Dilution FlowFlowss

Diversion of Columbia River water viviaa Rocky Coulee WasteWastewayway into MoMosesses Lake isis managed by United States Bureau of Reclamation. Dilution flofloww began inin 1976.1976. FlowFlow delivery to Moses Lake isis basebasedd on irrigationirrigation neneedseds south of Moses Lake. ConsequConsequentlyently flows aarere provided regularly inin the spring aandnd fall to fill tthehe Potholes Reservoir. Flows are intintermittentlyermittently released in tthehe summer. Figure 5 shshowsows dilution flows from Rocky Coulee WastewaWastewayy intointo Moses Lake throthroughoutughout 20020055 and also thrthroughough July 2006. This figure shows the general pattern of flow; large flows in spring and fall and lessless inin tthehe summer and winter.

WRIA 41 LoLowerwer Crab CCreekreek 18 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

c: we m Thai! :r

\ new a” - ‘ \ . \

+Mile 2

2/? Crest Inland ‘\. ,7, W ‘ mgr {man-“4L5 7

Figure 3. Detail - Vicinity Map of Cascade Valley and Lake Sampling Stations.

|-L.R

III

--I

...... E .l-IFIIJUH In

_._' mm .

kl- “(new

ILlIl.

' WHMWHQI‘MJ

.kxutuu } ‘- _ h. 2-H . "WP-HE I.I' I F' 'llllHlw...-

I..Iul|-I-II--'ll.

4.1

l-.

3._.

.-. .1'.-\'L

.J " Figure 4. DeDetalltail 'VI‘c‘iVicinithityy MapMap‘bf of PelicaPelicann HornHorrl Ehdand ‘LakeLake SamplingSahib-"HQ StationS'téi'ieri‘SLIs. "

WRIA 41 LoLowerwer Crab CCreekreek 19 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Flows from Rocky CoulCouleeee have significant impacts on nutrient levels and water ququalityality in the lake.lake. Total fflowlow to MoseMosess Lake in 20200606 was 194,802194,802 acre-feet. This was significantly less than flow added inin six previous years ((TableTable 7). From 2002 through 20020055 total annuannualal flow was greater than 316,900 ac-ac-ftft for each year.

Year Dilution Release Year (ac(ac-ft)-ft) 19197676 64,070 19197777 150150,630,630 19197878 81,840 19197979 214214,540,540 19198080 19,54019,540 19198181 56,050 19198282 144144,180,180 19198383 73,250 19198484 0 19198585 154154,350,350 19198686 106106,230,230 19198787 137137,770,770 19198888 207207,300,300 19198989 207207,300,300 19199090 229229,980,980 19199191 286286,098,098 19199292 267267,846,846 19199393 120120,976,976 19199494 289289,356,356 19199595 132132,211,211 19199696 60,685 19199797 25,886 19199898 111111,026,026 19199999 117117,928,928 20200000 243,07243,0722 20200101 242,039 20200202 316,900 20200303 340,41340,4188 20200404 372,315 20200505 326,875 20200606 194194,802,802 90th percpercentileentile 316316,900,900 75th percentilepercentile 242,55242,5566 50th percpercentileentile 150150,630,630

Table 7. MosMoseses Lake Dilution WaWaterter Release RecoRecord.rd.

Total annual flow is not always a gogoodod indicator of lake quality during the summer bebecausecause significantly less dilution flofloww isis available inin the summer months. FigureFigure 5 sshowshows that in 2006 mosmostt of the dilutiodilutionn flow were added beforbeforee July 1;1; of 194,000194,000 acracre-fte-ft added in 2006 only 87% of tthehe annual flow was releasereleasedd before July 1.1. TherefThereforeore dilution flows inin July, August, and Septem- ber were veveryry lowlow in 2006. This wwasas a major factor in high concentrations of TP aandnd algae in the September lakelake sasamples.mples.

WRIA 41 LoLowerwer Crab CCreekreek 20 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

5000 2 + 22005005 RRockyocky CCouleeoulee WWastewaterastewater 4500 . III 22005005 Lake ssampleample 7 —I— 22006006 RRCC WWastewayasteway 3 El 22006006 Lake ssampleample 4000 K

3500 i t

a:f 3000 - e r 1 “i° ac 2500 I 9, 1 ow

_0l LLgF 2000 l, @ﬂiﬂk . 4 15001 500 l .1

1000 a I i

500 l ,’_..._———o———o—-*é 4

0 #9 1/1/11 22/1/1 33/1/1 44/1/1 5/5/11 66/1/1 77/1/1 88/1/1 9/9/11 110/10/1 11/11/11 12/12/11 MMonths,onths, 22005005 Figure 5. CoComparisonmparison of Dilution floflowsws from RoRockycky Coulee WasteWastewayway inin 2005 and 202006.06.

6.3.3 Lake Water Quality -- Phosphorus

The lake wawass sampled oonn July 26th and on September 21215‘.st. On both days surface wwaterater grab samples were collectecollectedd at all lake ststationsations (Table 8). Surface water coconcentrationsncentrations of TP were lessless than 40 ug/L at all locationslocations inin July. InIn September surface water sasamplesmples were greater than 50 ug/L TP at three stations. TThehe average surface watwaterer concentraconcentrationtion for the eentirentire lakelake was 26 ±1r 1212 ug/L TP in July and 54 ±1r 1414 ug/L TP in September.

The elevated TP in September occurs for several reasons, 1)1) TP release fromfrom the sediment increase in ththee summer ddueue to development of anoxic sediment conditionconditions,s, 2) a uniforuniformm temperature gradiengradientt facilitatesfacilitates mixing of the entire water column, and 3) dilutiodilutionn flow was lowlow inin August and September. These three conditconditionsions combincombineded resulted in elevated TP concentraconcentrationstions and the eutrophic conditions observed.

6.3.4 Lake Water Quality —– Algae, ChlorophChlorophyll,yll, and Visibility

Lake Sampling Results

Surface water samples were sent to Water Management Laboratories aandnd analyzed for algae type and chlorophyll a. The algae ddensitiesensities (Ta(Tableble 9) and chlorophyll a (Table(Table 8) were much higher in SeSeptemberptember than in July. TThehe algae popopulationspulations wewerere dominated by toxic blue green algae during both July and SeptembSeptember.er. Concentrations were highest inin SSeptembereptember and toxic blue green aalgaelgae were at levels that have moderate to high pprobabilityrobability of adverse health effects. The World Health Organization conconsiderssiders conconcentrationscentrations grgreatereater than 1100,00000,000 councounts/100ts/100 mL a moderate risk (WHO 2006). During this type of condition, the WHO recorecommendationsmmendations are to discourage swimming and post on-site risk advisory signs. TThehe risks are greatest frofromm the toxic blue-green algae Microcystis sp. ThThisis alga was at elevated concentratioconcentrationsns throughothroughoutut the lake inin September. Concentrations inin ththee southern ppartart of the lake were highest, reachinreachingg concentrations of 5554,00054,000 at ML3.0 and 70704,0004,000 countcounts/mLs/mL at ML7ML7.0.0 (Figure 4 and Table 99).). ItIt isis

WRIA 41 LoLowerwer Crab CCreekreek 21 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

common for these algae species to ddriftrift with the winds and ggetet concentraconcentratedted inin down wind sec- tions of a lalake.ke. The high concentrations inin SepteSeptembermber are most likelikelyly due to strong nnortherlyortherly winds the ddayay before sampling. The day before sampling, September 20, the winds were blow- inging to the sosouthuth at an average speed of 3.6 mmph;ph; significantly higher than tthehe monthly average ofof2.1 2.1 mph.

Table 8. SummarSummaryy of lalakeke sampling during 2002006.6. MLCCMLCCO0 MML2.0L2.0 MML2.5L2.5 MML3.0L3.0 MML4.0L4.0 MML5.0L5.0 ML6ML6.0.0 MML7.0L7.0 TTP,P, uug/Lg/L 77/26/06/26/06 3355112244663399 9 117733221155 9/219/21/06/06 2299 59 nnss 69 49 37 47 62

OrOrthotho - PP,, ug/L 77/26/06/26/06 33445 010 17744 515 18855 9/219/21/06/06 6 9 nnss 1133 9 5 8 1212

TTotalotal N, mg/L 7/267/26/06/06 <<0.70.7 <<0.70.7 11.95.95 11.3.3 <0.7 <0.7 0.7 <<0.70.7 9/219/21/06/06 <<0.70.7 <<0.70.7 <<0.70.7 <<0.70.7 <<0.70.7 <<0.70.7 <<0.70.7

pH 7/267/26/06/06 88.3.3 8.76 7.98 8.6 88.55.55 88.61.61 88.77.77 88.71.71 9/219/21/06/06 77.9.9 8.6 nnss 88.7.7 8.5 88.8.8 8.7 66.99.99

TTemperature,emperature, ooCC 7/267/26/06/06 23.3 26.1 23.8 25.9 26.7 27.5 2277 26.26.33 9/219/21/06/06 13.813.8 18.018.0 nnss 18.118.1 17.8 16.216.2 17.517.5 18.18.00

DisDissolvedsolved oxoxygen,ygen, mg/L 7/267/26/06/06 77.15.15 99.16.16 77.98.98 88.2.2 8.67 10.510.566 7.99 8.08.033 9/219/21/06/06 88.3.3 10.710.7 nnss 88.4.4 10.410.4 10.010.0 99.7.7 9.5

SSecchiecchi dedepth,pth, ft 7/267/26/06/06 55.2.2 6.8 12.212.2 66.3.3 4.5 66.5.5 10.10.88 9/219/21/06/06 77.0.0 3.3 nnss 22.3.3 3.9 55.2.2 ns 2.3

ChloChlorophyllrophyll aa,, ug/L 7/267/26/06/06 nnss5nnss56755 6 7 5 1144 9/219/21/06/06 4 2200nnss2299116611222277 9

WRIA 41 LoLowerwer Crab CCreekreek 22 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING

Table 9. DenDensitiessities of algaalgaee in the lake inin July and SeptembeSeptember.r. 21-Jul21-Jul-06-06 9/21/2009/21/20066 MML2.0L2.0 MML2.0L2.0 PhytoplankPhytoplanktonton ccounts/mLounts/mL ccounts/mLounts/mL Total 220,40220,4000 544,00544,0000 Microcystis (59%), AphanizomenonAphanizomenon Microcystis (59%), Bluegreen Lyngbya (33%o ), Apha-_ 220,000 (87%), Microcystis 500,000 B'uegre‘?“(Toxic) 220,000 (87%), Microcystis 500,000 nizomLyngbyaeno(3313}n (3%),Apha Ana- (TOXIC) (13%)(130/) nizomenon (3 An), Ana- ° baenbaenaa (5%) MML3.0L3.0 MML3.0L3.0 PhytoplankPhytoplanktonton ccounts/mLounts/mL ccounts/mLounts/mL TTotalotal 44,100,100 800,40800,4000 Microcystis (76%), BluegreenBlue reen Microcystis (76%), g . 22,000,000 MMicrocystisicrocystis (1(100%)00%) 730,00730,0000 Lyngbya (6%(6%),), Apha- (Tox(TOXIC)ic) . o nizomnizomenonenon (3%),An), ML4.0 PhytoplankPhytoplanktonton ccounts/mLounts/mL ccounts/mLounts/mL TTotalotal 661,9001,900 625,90625,9000 Ulothrix AphanizomenonAphanizomenon AnabaenAnabaenaa (5(58%),8%), Mi- Bluegreen (66%), Microcystis crocystis (31%), Lyng- Bluegreen 59,500 (66%), Microcystis 600,000 crocystis (31%), Lyng- (Tox(Toxic)ic) 59500 (30%), AnaAnabaenabaena 600’000 bya (3%), Aphanizome-Aphanizome- (4%(4%)) non (8%(8%),), MML5.0L5.0 MML5.0L5.0 PhytoplankPhytoplanktonton ccounts/mLounts/mL ccounts/mLounts/mL TTotalotal 331,8001,800 626,10626,1000

AnabaeAnabaenana (6(65%),5%), Micro- Bluegreen cystis (28%), Apha- Bluegreen 7,100 Anabaena 600,000 cystis (28%), Apha- (Tox(Toxic)ic) 7’100 Anabaena 600’000 nizomnizomenonenon (6(6%),%), Lyng- bya (1%)

MML6.0L6.0 MML6.0L6.0 PhytoplankPhytoplanktonton ccounts/mLounts/mL ccounts/mLounts/mL TTotalotal 114,6004,600 269,60269,6000 Microcystis (87%), Ana- BluegreenBlue reen Microcystis (87%), Ana- 9 . 110,1000,100 MMicrocystisicrocystis (1(100%)00%) 200,00200,0000 baenbaenaa (9%), Apha- (Tox(Toxnc)ic) . o nizomnizomenonenon (4%)A) MML7.0L7.0 MML7.0L7.0 PhytoplankPhytoplanktonton ccounts/mLounts/mL ccounts/mLounts/mL TTotalotal 1160,00060,000 867,30867,3000 GreeGreenn <20<2000 <<200200 Aphanizomenon Microcystis (88%), Ana- BluegreenBlue reen Aphanizomenon Microcystis (88%), Ana- (goxic) 160,00160,0000 (93%(93%),), MiMicrocystiscrocystis 800,00800,0000 baenbaenaa (11%(11%),), Lyngbya (Toxic) (7%(7%)) (1%(1%)) CC 0 CC 0 PhytoplankPhytoplanktonton ccounts/mLounts/mL ccounts/mLounts/mL TTotalotal nnss 77,100,100 Bluegreen Bluegreen ns 700 (Tox(Toxic)ic) “5 70° MicrocyMicrocystisstis (1(100%)00%)

ns = nnoo sasamplemple

WRIA 41 LoLowerwer Crab CCreekreek 23 AF WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

The liver toxins from thethesese algae can cause skiskinn irritations, gastrointestgastrointestinalinal illness, and potential longlong term illness.illness. Pets are most vulnerable due to potential ingestioningestion frofromm drinking oorr lickinglicking the algae off thetheirir fur.

These blue green algae are associaassociatedted with lakes with elevated concenconcentrationstrations of pphosphorus.hosphorus. InIn September, the average concentconcentrationration of TP inin the surfsurfaceace water ooff the lakelake wwasas 54 ug/L. Elevated concentrations of phosphorus contributcontributee to the elevated concentrations of blue green algae.

General Background on Blue Green AlqaeAlgae

Blue-green algae are ubiquitous in ponds and lakes around the world. TTherehere are nunumerousmerous species of blue-blue-greengreen algae; most do nnotot produce toxins. FourFour primary gengeneraera grow in Washington and produce toxins. These four genera are MMicrocystisicrocystis spsp.,., Anabaena spsp.,., AphanizomenonAphanizomenon spsp.,., and GloetrichiaGloetrichia spsp.. All genera are capable of prproducingoducing microcystin, a hhepatoepato (liver) toxin, bubutt Microcystis is to be the major producer of microcystin.

Microcystin and other cyanotoxins have not beebeenn didirectlyrectly relatedrelated to deaths of humanhumanss from rec- reation inin ponds or lakelakes.s. However, there have been links ttoo skin rasherashess on swimmers and clo- sure of swimming areaareass is commocommon.n. The toxin presents ththee greatest ddangeranger to pepeopleople when it occurs in ddrinkingrinking water reservoirs. The World Health OrganizatioOrganizationn has set an allowable cyanotoxin concentratioconcentrationn of 11 µug/Lg/L (1(1 part per billion) for ddrinkingrinking water. This isis ththee concentraconcentra-- tion that thetheoreticallyoretically cocoulduld be consumed in drinking water by a human being evereveryy day for 70 years withowithoutut illill effect (Newcomb(Newcombee and Burch, 2003). ConcentrationConcentrationss recorded in western Washington lakes,lakes, have been as high as 32 µug/Lg/L in Green Lake (Seattle DepartmeDepartmentnt of Parks 2003) and 43 ug/L in LaLakeke SammaSammamishmish (Jacob(Jacobyy 2003). InIn ponds and lakes used strictly for rec- reation the primary concern is consumption of water by to pets and livestock.livestock. TherTheree have been deaths of pepetsts attributed to cyanotoxins.

No attempt was made to measure cyanotoxins in Moses LaLakeke in 202006.06. Future sampling shoushouldld monitor microcystins espespeciallyecially in pupublicblic swimming and livestock waterinwateringg areas.

6.3.5 Lake Trophic Status

Washington State Department of Ecology regulates nutriennutrientt loadsloads to water bodies inin order to maintain the lake trophic status (W(WACAC 173-201173-201A—010(6)).A-010(6)). Critical months for determination of the trophic status index (TSI)(TSI) are June through September. Trophic ststatusatus claclassificationsssifications foforr ponds are ooligotrophic,ligotrophic, mesotrophic, and eutropeutrophic.hic. OligotroOligotrophicphic ponds are low in nnutrientsutrients (i.e.(i.e. Lake ChelaChelan);n); eutrophic systems are high inin nutnutrients.rients.

Eutrophication is a natunaturalral process of accumulaaccumulationtion of nutrienutrientsnts that caucausesses a changchangee in the trophic status of a water bbody.ody. This process can bbee greatly accelerated by human activities. EutroEutro-- phication may result inin excessive growth of aquaquaticatic plaplants,nts, lossloss of fish hhabitat,abitat, and inin worst-case largelarge fish kills. InIn the lastlast couple ooff decades, toxic blue green algae have also become more problematic in eutrhophic lakes.

Trophic Status IndexIndex (T(TSI)SI) is calculated for the average ssummerummer (June through September) concentratioconcentrationsns of TP. CChlorophyllhlorophyll a, and secchi depth disk. The followinfollowingg equations from Carl- son (1977) are used to calculate ththee TSI.

WRIA 41 LoLowerwer Crab CCreekreek 24 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

TSI for Total Phosphorus: TSITSlTpTP = 14.4214.42 * lnIn (TP, ug/L) + 4.14.155

TSI for Chlorophyll a: TSITSICHL=CHL= 9.81 * lnIn (Chl a, ug/L) + 30.6

TSI for secchi depth: TSITSISDSD = 60 –—14.41*ln 14.41*ln (SD,(SD, m)

A TSI greater than 40 indicates memesotrophysotrophy and a TSI greater than 50 indicates eeutrophyutrophy (Ca(Carl-rl- son 1977).1977). InIn order for Moses Lake to be inin a mesotrophic conditconditionion the average TP would need to be less than 23 ug/L.

During 2006, the averagaveragee TSI for all indicesindices werweree above 50 iindicatingndicating a eutrophic cocondition;ndition; the TSITSITPTP = 56, the TSITSICHLCHL = 54, and the TSITSISDSD = 53.

The elevated TP and eeutrophicutrophic stastatete of the lalakeke is not sursurprisingprising considering the small dilutiodilutionn feed going to the lakelake inin July –— SeSeptemberptember (Figure 5). The data exeexemplifymplify the iimportancemportance of regular dilution flow throughout the summer monmonths.ths.

6.4 LAKE SSEDIMENTEDIMENT SAMPLING

Under the direction of DDonon Beckley, sediment sasamplesmples and depths were taken from Laguna and Wild Goose Inletslnlets on SeSeptemberptember 21, 2006. The depth of the sediment above cobbles was measured with a long ststeeleel rod. ItIt was pushed into the sediment until it would stop with two men pushing on it. The point at which it stopped was consideconsideredred to be ththee depth of ththee cobbles. The sites anandd depths are shown inin TTableable 10.10. ThThee samples were both taken from Laguna. The sample taketakenn in the LagLagunauna channel was a silt loloam;am; with 65% silt and 115%5% clay. This sample had strong sulfide odors when it was collected imimplyingplying anoxic sediments. Anoxic sediments will increaincreasese release of pphosphorushosphorus frfromom the sediment. Phosphorus levels in the sedsedimentiment were 10001000 mg/kg. The sample collectcollecteded at the inlet ooff the Laguna channel wawass a loamy sand which also had ababoutout 10001000 mg/kg of total pphosphorus.hosphorus. This sample was not anoxic. Sediment analysis is in AppendixAppendix 3.

6.5 CRAB CREEK SSAMPLINGAMPLING

The United States Bureau of ReclaReclamationmation initiainitiatedted the suppsupplementallemental feed study (WA(WA DOE 2006) inin August 202006.06. Sampling of Crab Creek and Rocky Ford Creek startestartedd in August 2006 and collected ununtiltil December 2006. Supplemental flows ended December 115‘“,5th, 2006.

The expected flow path for the supplemental feed water was from Brooks Lake throuthroughgh the Town of Stratford and ddownown the Crab Creek drainage into Moses Lake. There were several fal- lowlow fields anandd open ground that the water could runrun through so erosion, sediment, and nutrient transport intintoo Moses Lake was a coconcern.ncern. A sasamplingmpling plan was initiated to monitor the impactimpact of the expected flows on Crab Creek and itsits discharge intointo Moses Lake. Sample locations and descriptiondescriptionss are shown in Table 11.11.

The USBR report for the supplemental flow study has not beebeenn released. Therefore the actual flows are nonott known at tthishis time. Verbal reportsreports are that 100100 to 150150 cfs ooff water was diverted during the ststudy.udy. Figure 6 shows thathatt flows inin Crab Creek did not increaincreasese until earearlyly October. The flow intintoo Crab CreeCreekk increaseincreasedd by 20 to 40 cfs in OctobOctoberer and NoveNovembermber then increased dramatically again in DeDecember.cember. The peak December flow of 95 cfs wawass about 75 cfs greater

WRIA 41 LoLowerwer Crab CCreekreek 25 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

than the seaseasonalsonal average. ItIt appeappearsars that if ththee supplemental flow stustudydy had continued a significant portportionion of the flofloww would have runrun from Crab Creek intointo Moses Lake.

Table 10. SeSedimentdiment samsamplingpling sites in Laguna anandd Wild Goose InletsInlets on 9/29/21/06.1/06. SSiteite DescriDescriptionption CoCoordinatesordinates 11 LagLaguna/Pieruna/Pier 4 CChannelhannel 47 6.051 119119 119.7179.717 WWaterater Depth 33.8.8 fftt PrProbeobe dedepthpth ((toto wwaterater ssurface)urface) 1212 fftt DeDepthpth of ssandand aandnd ssiltilt ssedimentediment 8.2 fftt OOnene sedsedimentiment sampsamplele cocollectedllected ponaponarr grgrad,ad, sstrongtrong ssulfideulfide ssmell,mell, ffineine ssedimentediment and rrnnteoots OGM?M? 2 LagLaguna/Pieruna/Pier 4 CChannelhannel - westwest of docdockk 4477 66.057.057 119119 119.6539.653 WWaterater Depth 22.6.6 PrProbeobe dedepthpth ((toto wwaterater ssurface)urface) 1212 DeDepthpth of ssandand aandnd ssiltilt ssedimentediment 9.4 No ssampleample

3 LagLaguna/Pieruna/Pier 4 CChannelhannel - eaeastst of eendnd of 47 6.058 3 47 6.058 docdockk 119119 119.6019.601 WaWaterter DDepthepth 3 PrProbeobe dedepthpth ((toto wwaterater ssurface)urface) 7.6 DeDepthpth of ssandand aandnd ssiltilt ssedimentediment 4.6 No ssampleample

LagLaguna/Pieruna/Pier 4 CChannelhannel - bebetweentween easeastt 4 47 6.051 4 end of doclockck anandd inlet 47 6'051 119119 19.5419.54 WaWaterter DDepthepth 3 PrProbeobe dedepthpth ((toto wwaterater ssurface)urface) 7 DeDepthpth of ssandand aandnd ssiltilt ssedimentediment 4 No ssampleample

LagLaguna/Pieruna/Pier 4 CChannelhannel - ssouthouth sSideide of 47 6.048 47 6.048 5 inleInlett 119119 19.5219.52 WWaterater Depth 22.8.8 PrProbeobe dedepthpth ((toto wwaterater ssurface)urface) 1212 DeDepthpth of ssandand aandnd ssiltilt ssedimentediment 9.2 OOnene sedsedimentiment sampsamplele no ododoror ffromrom ssample,ample, ccoarseoarse

6 WiWildld GGooseoose nnaa nnaa na na WaWaterter DDepthepth 3 PrProbeobe dedepthpth ((toto wwaterater ssurface)urface) 6 DeDepthpth of ssandand aandnd ssiltilt ssedimentediment 3 No ssample,ample, DO leslesss tthanhan 11 mmg/Lg/L

WRIA 41 LoLowerwer Crab CCreekreek 26 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING

Table 11. CrCrabab CreCreekek sasamplingmpling locations. QID NM Ww CCCOC0 47.14147.1416060 -119.2-119.268386838 CCC1C1 47.18947.1896464 -119.2-119.264016401 CC02C2 47.22547.2251717 -119.2-119.277437743 RRF17F17 47.26147.2615555 -119.4-119.455965596 DDL-10L-10 47.23447.2340101 -119.2-119.296669666 DDL-AFPL-AFP 47.22447.2247070 -119.2-119.288358835 DL-AFDL-AFDD 47.22247.2228585 -119.2-119.280638063

QID Description W bank of Crab Creek, S side of Hwy. 17 bridge at CCCCO0 W bank of Crab Creek, S side of Hwy. 17 bridge at mouth CCCC11 E bank of CraCrabb CreCreek,ek, S sisidede of Rd. 7-NE bridge, at USGS gaugingaugingg station CCCC22 W (S) bbankank of Crab CreeCreek,k, E side of StraStratfordtford Rd bbridgeridge W (N) babanknk ooff Rocky Ford CreCreek,ek, W sidsidee of Hwy. 1717 bridgbridge,e, adjaadjacentcent to bridge pillar with RF17 RF17 staff gage DL-10 Dairy LaLakeke at Rd 10-NE,10-NE, alalongong fenfencece linlinee N sidsidee of Rd. 1010 approx 25 ft W of cement draidrainn DL-10 acceaccessss pipipepe Dairy Lake at Paved Air Force Rd to old Nike site--D/S end of culvert under DL-AFPDL AFP Dairy Lake at Paved Air Force Rd to old Nike site--D/S end of culvert under ' roadroad Dairy Lake at Dirt Air Force Rd to NE exit—no culvert, W edge of road; installed staff DL-AFDL-AFDD Dairy Lake at Dirt Air Force Rd to NE exit—no culvert, W edge of road; installed staff gage

Although floflowsws increaseincreasedd significantly for the seasseasonon they were not greater than peak flows that have been measured in Crab Creek (Carroll 2006). The peak flows of 75 - 95 cfs did not result inin signifsignificanticant changes inin water qualitqualityy in Crab Creek (Table 112).2).

Supplemental feed flow also increaincreasedsed flows in Rocky FordFord Creek. The flow increase was most significant in December 2006 and JaJanuarynuary 2007 and has concontinuedtinued intointo March 2007 (Figure 7). There are no continuoucontinuouss flow gages but staff gagagege readings were providprovideded by USGS and USBR for Rocky Ford Creek below the hatchery (Appendix 5).

The increased groundwater flows to Rocky FordFord Creek could have one of two resultresults;s; it coucouldld 1)1) decrease ththee TP conceconcentrationsntrations by dilution or 2) itit could havhavee no change on TP.

Concentrations of both fformsorms of phosphorus (TP and OP) anandd nitrates inincreasedcreased sigsignificantlynificantly inin Rocky Ford Creek during October, NoveNovembermber aandnd December (Table 1212).). This appeappearsars to be a normal trend for Rocky Ford Creek (Carroll 2006, Cusimano and Ward 1998)1998) and cannot be directly attribuattributedted to the susupplementalpplemental flow study.

The elevated TP and increased floflowsws will resulresultt inin increaincreasedsed loads of TTPP to Moses Lake. This may be a tratransientnsient condconditionition and neeneedsds more consideration wwhenhen the final report from USBR is available.

Land surrousurroundingnding a dairdairyy on Crab Creek became flooded duduringring November. FieldsFields tthathat were regularly used for land aapplicationpplication of dairy waste became flooded. A pond that formed was sampled and had elevated levels of phosphorus (Table 13).13). The pond ththatat was formed threat- ened to breach a3 naturanaturall leveelevee and flood Crab Creek. The ppondond did not breach the levee and slowly disapdisappearedpeared after the study was completecompleted.d. The water percolated back into ththee soil but

WRIA 41 LoLowerwer Crab CCreekreek 27 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

the fate of ththee phosphoruphosphoruss isis unknown. This dairdairyy would need to be closed or moved inin order to minimize impacts of a supplemental feed route down Crab Creek.

Table 12. CrCrabab CreCreekek waterwater quality resultsresults prior aandnd during flofloww aaucugmenmentationtation studstudyy bbyy USBR. Total PhospPhosphorus,horus, ug/LuglL (ppb) l l l CraCrabb CreeCreekk Sampling SiteSitess DDateate CCCCOO CCCC’I1 CCC2C2 CCC3C3 CCCC44 - CCCC44 - RF17 E W CroCrossss crocrossss

88/11/06/11/06 3300 2288 2288 2266 nnss nnss 113939 99/26/06/26/06 3311 3399 4466 3355 6644 113030 nnss 110/13/060/13/06 4477 3322 5577 nnss nnss nnss nnss 110/26/060/26/06 2266 4455 5555 nnss nnss nnss 117474 111/2/061/2/06 3311 4422 4444 nnss nnss nnss 119292 112/5/062/5/06 6655 5511 2277 nnss nnss nnss 119191

Ortho PhoPhosphorus,sphorus, ug/L (ppb) 88/11/06/11/06 1122 1133 1122 1100 0 0 7744 99/26/06/26/06 2222 1188 2211 2277 2211 3377 nnss 110/13/060/13/06 2244 2233 2200 nnss nnss nnss nnss 110/26/060/26/06 1111 3333 3300 nnss nnss nnss 110909 111/2/061/2/06 2266 3355 1199 nnss nnss nnss 116868 112/5/062/5/06 2288 <<22 2 nnss nnss nnss 8899

Total SuspeSuspendednded Solids, mg/L 88/1/111/06/06 8 9 1122 9 11 0 2222 99/26/06/26/06 <<11 <<11 <<11 <<11 <<11 <<11 <<11 110/13/060/13/06 <<11 <<11 <<11 nnss nnss nnss nnss 110/26/060/26/06 <<11 <<11 2 nnss nnss nnss 1133 111/2/061/2/06 <<11 <<11 <<11 nnss nnss nnss 2 112/5/062/5/06 7 5 11 nnss nnss nnss 2200

NitraNitratete anandd Nitrite, mg/L 88/11/06/11/06 11.31.31 11.1.1 11.07.07 00.08.08 nnss nnss 11.34.34 99/26/06/26/06 11.33.33 00.93.93 11.16.16 00.54.54 11.12.12 00.053.053 nnss 110/13/060/13/06 00.85.85 11.38.38 00.79.79 nnss nnss nnss nnss 110/26/060/26/06 00.44.44 00.74.74 00.69.69 nnss nnss nnss 22.08.08 111/2/061/2/06 00.89.89 11.02.02 00.96.96 nnss nnss nnss 22.17.17 112/5/062/5/06 11.93.93 11.49.49 00.95.95 nnss nnss nnss 11.79.79

WRIA 41 LoLowerwer Crab CCreekreek 28 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING

'3 1w 3 EH :5 an

9.2 EHTB _ ___l,_,-‘-J.-_I id”..-Isl-y! magi; . u m . h-E-i-‘L

H-a .” -" E. '2 an L1

r.ii EB I'l .: U a u-l : 3. .I H 13 3 Jul 81 H1201 Sell 01 But Eli "In! I11 Dec 31 Jan E1 Feb Bil 2905 2MB 20% 2905 2“ M95 298? 2190?

— I'ledlan dallg statistic {55 years} — Period of improved data — Daily Hem discharge Period u-F wwiﬁnnal data — Estlnated dailg nean discha‘ge

Figure 6. CraCrabb CreeCreekk floflowsws during USUSBRBR flofloww aaugmentationugmentation frfromom BrookBrookss Lake. FloFloww aaugmenta-ugmenta- tion occuroccurredred from early AuguAugustst to December 115th5th 2006.

9090.0.0 8080.0.0 7070.0.0 6060.0.0 s f cfs 50.0

c 50.0 , w ow

o 4040.0.0 fl fl 3030.0.0 2020.0.0 1010.0.0 0.0.00

r y h e y c b ber ar ar ar mber to mber nu u e em e a m oc ov ec J febr sept n d

El 22004004 - 20200505 UUSGSSGS ((2007)2007) l 22006006 - 20200707 ((USBRUSBR 202007)07) El CCarrollarroll 20200606 ((estimatedestimated ffromrom FFigureigure 7, p1p19)9)

Figure 7. CoComparionsmparions of Rocky Ford flofloww durinduringg ssupplementalupplemental feed sstudytudy ((2006-2007)2006-2007) withwith prevpreviousious flofloww rrecords.ecords.

WRIA 41 LoLowerwer Crab CCreekreek 29 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

7.0 GROUNDWATER

GroundwateGroundwaterr samples were collectcollecteded from monitmonitoringoring wells locatedlocated at ththee Larson WWastewaterastewater Treatment Plant (WWTP), private domestic wells, and wells sampled by Bain (2002) ((FigureFigure 9). WWTP monmonitoringitoring wells are identifieidentifiedd by MW-1, MW-2, MW-3, and MW-4MW—4 (MW-1 wawass not sampled because this well is often too drdry),y), private ddomesticomestic wells are identifidentifiedied by the Washington DOE six-digisix-digitt well identifier,identifier, and wells and sitesitess prpreviouslyeviously sampled by Bain (2002) aarere identified by the designations G-1 through G-8. Table 1414 ppresentsresents more detailed ininformationformation for each well includingincluding tthehe well identifidentifier,ier, depth, ggeologiceologic matmaterial,erial, and ththee specific paparcelrcel or addraddress.ess.

DL-g‘F-rD Q

006 Navleq ‘ g. 2006 Europa Technologies Painter l'a'l 412273305 Inn -119 235387' alov 1111It Slraamln- ll l l H 100%:- Figure 8. Sampling sites on Rd 10 DaiDairyry during flflowow aaugmentationugmentation studstudy.y. Approximate flooded area is shoshownwn (map from Google Earth).

7.1 PHOSPPHOSPHORUSHORUS IN MUNICIPAL WASTEWATERWASTEWATER EEFFLUENTFFLUENT

Larson WWTP is locatelocatedd on a 34 acre site southsoutheasteast of the Grant CountCountyy Airport (Figure 9). There is a lolongng history at this site of wastewater disposal intointo rapid infiltrainfiltrationtion basinbasins.s. InIn 1943,1943, a primary treatment plant was constconstructedructed on ththee site to serserveve the Larson Army Air Corp Base includingincluding bbasease housing. InIn the early 1970’s1970’s the city upgraded the originaoriginall primary wawastewaterstewater treatment facility and coconstructednstructed ththee current LaLarsonrson WWTP (WA DOE 22001001).).

The WWTP serves approximately 55000000 residentresidents.s. Between July and December 2006 this facility disposed of 350,000 to 4400,00000,000 gallogallonsns per day. Concentrations of phosphorus, chlochloride,ride, so-

WRIA 41 LoLowerwer Crab CCreekreek 30 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

dium, and boron from the wastewater effluent araree shown in Table 15.15. TThehe average daily flow for the year wawass 324,000 ggpd.pd.

There is conconcerncern that phphosphorusosphorus lloadingoading to grogroundwaterundwater from WWTP reresultssults in a nenett loadload of pphosphorushosphorus to Moses Lake. Sampling during 20020066 found that groundwater from all the WWTP monitoring wells have elevated levels of TP (Table 16).16). Chloride, sodium, aandnd bboronoron werewere aalsolso all very high and at concentrations simsimilarilar to those found inin ththee wastewater.

Well MW-3 mean groundwater TP and OP concentrations araree bbyy farfar tthehe hhighestighest aandnd compare ccloselylosely ttoo tthehe mean Larson WWTP wastewater effluent conceconcentrationsntrations (T(Tablesables 1515 anandd 16):16): 2614 ug/L TP wastewater and 2079 ug/L TTPP at MW-3; 22299299 uug/Lg/L OOPP wastewaterwastewater aandnd 11934934 uug/Lg/L OOPP at MW-3. This is due to tthehe location of MW-3, which is tthehe most down-gradient well in the main southwest ggroundwaterroundwater flow direction from the WWTP wastewater infiltrainfiltrationtion ponds.

Table 13. WaterWater quality from flood popondnd around ddairyairy on Road 10. Dairy LaLakeke at USAF Paved Rd USAF Dirt Rd Date RD 1100 (D(DL-L- at CULVECULVERTRT LEVEE (DL- 10)10) (DL-AFP)(DL-AFP) AFD)

Total phophosphorus,sphorus, ug/L 11/2/0611/2/06 267 570 350 112/5/062/5/06 119999 469 347 Ortho phophosphorus,sphorus, uug/Lg/L 11 11/2/06/2/06 224747 445959 7733 112/5/062/5/06 110606 360 146146 Total SuspeSuspendednded SolidSolids,s, mg/L 111/2/061/2/06 <<11 <<11 1155 12/5/0612/5/06 <1 <1 7 NNitrateitrate + NNitrite,itrite, mmg/Lg/L 111/2/061/2/06 <<0.150.15 0 <0.15 112/5/062/5/06 0 0 11 DDissolvedissolved OOxygen,xygen, mmg/Lg/L 111/2/061/2/06 113.83.8 19.819.8 14.014.0 112/5/062/5/06 NNss ns ns TTemperature,emperature, o°FF 111/2/061/2/06 338.58.5 37.0 38.8 112/5/062/5/06 nnss ns ns

ppHH 11/2/0611/2/06 7.5 8.2 7.9 112/5/062/5/06 88.3.3 8.3 8.4

SShannonhannon aandnd WWilsonilson ((1989)1989) also repreportedorted groundwater phosphorus concentrations inin the moni- ttoringoring wwellsells iinn tthehe ssameame cconcentrationoncentration rangesranges thathatt are reportedreported for 2006. This shows that the soils benebeneathath this site hhaveave been heavily loaded for more than two decades. The average concentration difference betbetweenween the wastewater and MW-3 ground water is 535 ug/L TTP.P. This represents aaboutbout a 20% reduction inin TP. Long term use of this site for wawastewaterstewater ddisposalisposal aandnd the coarse hhighlyighly permepermeableable gravels is expected to have significantly rereducedduced aanyny ccapacityapacity fforor adsorption oorr precipitatioprecipitation.n. The reduction is probprobablyably due to dilution in ththee groundwater rather than removaremovall inin the sosoilil column. The estimated potential loadload to the grougroundwaterndwater dduringuring tthehe ssixix month sampsamplingling was aboaboutut 601 kg TTPP (Table 14).14).

WRIA 41 LoLowerwer Crab CCreekreek 31 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

, . .446119 1 Larson WWTP 1 ‘

' MW 4 G-7 MW—1‘.\. — I MW_3 o‘ .0 MW_2 188714

G-3 8-4 0 G-5 G-2 ' .0 G-1

432727 .545

176529 '382022

. 370489 G-8 .

0 0.5 1 15 2Miles ‘ 55: 47 1 Figure 9. WeWellslls and GrouGroundwaterndwater SaSamplingmpling LocaLocations.tions.

Table 14. Estimated monthly loadsloads to groundgroundwaterwater ffromrom tthehe LLarsonarson WWTP in 2006. MontMonthlyhly AAvg.vg. MontMonthlyhly MontMonthlyhly Total P CoCon-n- MontMonthlyhly Total FloFloww Total FloFloww centracentrationtion Total P LoLoadad MontMonthh (2(2006)006) (milli(millionon ggal)al) (milli(millionon LL)) (ug/(ugIL)L) (kg)(kg)

JanuarJanuaryy 99.670.670 336.606.60 nnss nnss FFebruaryebruary 88.844.844 333.483.48 nnss nnss MMarcharch 99.279.279 335.125.12 nnss nnss AAprilpril 99.308.308 335.235.23 nnss nnss MaMayy 99.763.763 336.966.96 nnss nnss JJuneune 110.1550.155 338.448.44 nnss nnss July 110.1880.188 338.578.57 3415 113232 AAugustugust 110.0330.033 337.987.98 33354354 127 SSeptembereptember 99.936.936 337.617.61 11995995 7755 OOctoberctober 99.959.959 337.707.70 11750750 6666 NNovemberovember 110.2890.289 338.958.95 11550550 6600 DDecemberecember 110.8280.828 440.990.99 33440440 141 Six-Month ns - not sampled. TTotalotal (k(kg)g) 601

WRIA 41 LoLowerwer Crab CCreekreek 32 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING

7.2 PHOSPPHOSPHORUSHORUS ANALYZEANALYZEDD FRFROMOM DOMESTIC AND OTHER AREA WELWELLSLS

GroundwateGroundwaterr phosphoruphosphoruss behavior inin the Moses Lake area can be furthefurtherr analyzed by exaexamin-min- inging groundwater phosphphosphorusorus concenconcentrationstrations from the domestic wells and tthosehose wells sampled by Bain (2002). Table 1188 summarizes groundwater data collected inin 20200606 from the domestic wells. SpecifSpecificic data for wwellsells and sitesitess G-1 through G-8 can be found in BBainain (2002). A spatial perspective of TP and OP groundwater concentrconcentrationsations from these wells isis displayed inin Figures 1010 and 1111 respectively (TP concentrconcentrationation data oonlynly are available for sitesitess sampled bbyy Bain (2002)).

Domestic wells 188714,188714, 176520,176520, anandd 446119 are shallow-dshallow-depthepth wells ((<100<100 ft) or are completed inin the more permeable upper flood sediments, or both. Groundwater samples show mean TP and OP concentrations inin the mid to higher rangrangeses above background lelevelsvels (>40 ug/L, Table 18,18, Figures 1010 and 11).11). Well 188714188714 isis locatlocateded in the main direction of grogroundwaterundwater flowflowjust just south of WWWTP.WTP. The high mean groundwater TP and OP concentratioconcentrationsns (>110 ugug/L/L OP and TP) mamayy be due to proximity to the wastewater disposal sitesite..

Table 15. IndIndividualividual Well InformaInformationtion

DeptDepthh ttoo Mid GeolGeologicogic MateriMaterialal l/ ForForma-ma- WWellell Tag or LaLabelbel for PoPosi-si- Screen or OpeOpenn tion of ConContributingtributing AAqui-qui- Well LocaLocationtion (Parcel Well IdenIdentifiertifier titiveve FielFieldd ID HHoleole (f(ft)t) fer or AAddress)ddress) a MW-1MW-1a MMW-1W-1 5599 Hanford/Hanford/RingoldRingold 111041200510412005 MMW-2W-2 MMW-2W-2 7700 Hanford/Hanford/RingoldRingold 119032400090324000 MMW-3W-3 MMW-3W-3 7700 Hanford/Hanford/RingoldRingold 111041200510412005 MMW-4W-4 MMW-4W-4 7711 RRingoldingold 111041200510412005 443272732727 AALE617LE617 110909 BBasaltasalt 112094700020947000 338202282022 AAKL565KL565 111919 BBasaltasalt 112112641021126410 b 117652076520 AACW245CW245 5959b GGravelravel 112210700022107000 337048970489 AAHJ844HJ844 110000 SSandstone,andstone, BasaBasaltlt 119049500090495000 188714 ACK712 73 Sand, Gravel, ClaClayy 190325010 446119 APC819 119 BroBrown,wn, Blue ClaClayy 121822417 G-1 IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium 170516000 G-2 IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium 170481000

PUD Well, Rd 7 east of G-3 IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium Stratford Rd Columbia Basin Hatch- G-4 (Spring)(Spring) IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium ereryy SpSpringring G-5 IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium 120903000 G-6 IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium 170611011 G-7 IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium ConnellConnellyy Park

G-8 IdentifiedIdentified from BBain,ain, 2002 na Upper Alluvium 141698000 a 8 MW-1 not samsampled;pled; well isis too drdry.y. b b Represents tottotalal wwellell depthdepth.. na —– not curcurrentlyrently available.

WRIA 41 LoLowerwer Crab CCreekreek 33 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUAUTY M ENGINEERING

Table 16. CoConcentrationsncentrations of phosphphosphorus,orus, chloride, sodium, and boron in Larson WWTWWTPP efflueneffluent.t. Total Phos- Ortho- Chloride Sodium Boron phorus (TP) Phosphate (Cl) (Na) (B)(B) (ug/L) (ug/L)(ug/L) (mg/L)(mg/L) (mg/L)(mg/L) (ug/L) MinimuMinimumm 11340340 11220220 442.92.9 774.44.4 115656 MaxiMaximummum 44560560 44090090 559.19.1 992.22.2 224848 MMeanean 22614614 22299299 448.48.4 882.92.9 118484 MMedianedian 22680680 22140140 447.97.9 882.32.3 117979 Standard DDevev 998181 884949 33.55.55 55.18.18 221.11.1

Domestic wells 432727, 382022, anandd 370489 are deeper wells (>100 ft) completed in the basalt rock units. GroundwateGroundwaterr from these wells contains mean TP and OP concentrations inin the lowerlower ranges near or below background lelevelsvels (<20 ug/L TP, <40 ug/L OP, Table 18,18, FigureFiguress 1010 and 11).11).

Table 17. 20200606 SummarSummaryy of GroundGroundwaterwater ParParametersameters from WWTP monitomonitoringring wwells.ells. Wells GrouGroundwaterndwater Parameters MWMW-2-2 MWMW-3-3 MWMW-4-4

Total PhosPhosphorusphorus (u(uglL)g/L) RaRangenge 80 - 210 1720 - 26266060 43 - 107 MMeanean 113535 22079079 559.59.5 MMedianedian 113333 11980980 5522 Number of SSamplesamples n = 7 n = 7 n = 7 OrthOrtho-Phosphoruso-Phosphorus (u(uglL)g/L) RanRangege 59 - 220 1520 - 27270000 1818 - 119 MMeanean 112020 11934934 6677 MMedianedian 110505 11830830 5588 Number of SSamplesamples n = 7 n = 7 n = 7 SodiuSodiumm ((mg/L)mg/L) Range 14.814.8 - 43.3 80.6 - 94.4 30.8 - 34.2 MMeanean 224.14.1 889.79.7 331.71.7 MMedianedian 118.98.9 991.91.9 331.41.4 Number of SSamplesamples n = 7 n = 7 n = 7 ChloriChloridede ((mg/L)mg/L) Range 2.4 - 31.2 43.4 - 49.9 8.9 - 11.411.4 MMeanean 111.01.0 446.56.5 99.6.6 MMedianedian 44.1.1 445.85.8 99.4.4 Number of SSamplesamples n = 7 n = 7 n = 7 a BBoronoron ((uglL)ug/L) a Range <2.08 - 78.7 140140 - 194194 <2.08 - 23.9 MMeanean 226.76.7 116565 116.86.8 MMedianedian 119.79.7 116868 220.20.2 Number of SSamplesamples n = 7 n = 7 n = 7 pH Range 6.50 - 7.11 6.88 - 7.03 7.30 - 7.62 MMeanean 66.90.90 66.95.95 77.53.53 MMedianedian 77.00.00 66.92.92 77.55.55 Number of SSamplesamples n = 6 n = 6 n = 6 TemTemperatureperature (C(C)) RanRangege 15.015.0 - 16.0 15.915.9 - 19.0 11.8 - 16.616.6 MMeanean 115.75.7 117.37.3 114.44.4 MMedianedian 115.95.9 117.07.0 114.64.6 Number of SSamplesamples n = 6 n = 6 n = 6 a a Soil Test LaborLaboratoryatory reporeportsrts <2.<2.0808 ug/L on 66-13-2006;-13-2006; 2.08 uug/Lg/L used in calculatiocalculations.ns.

WRIA 41 LoLowerwer Crab CCreekreek 34 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

The groundwater flow direction in ththee upper aquifer (in the Hanford/Ringold depositdeposits)s) from WWTP is in a south-soutsouth-southwesthwest direction towatowardrd Moses Lake ((MWH,MWH, 2001).). Two domedomesticstic wells sampled are located in tthishis flow diredirectionction from WWTP: wells 432727 anandd 382022 (Figure 10).10). These wells are completed in the babasalt.salt. Low TTPP concentraconcentrationstions inin thethesese wells imply that phosphorus is nonott moving inin to the basalt. Pitz (2003)(2003) sampled groundwater entering the lakelake inin this area and reported concentrations of 100100 to 178178 ug/L TP. Data collecollectedcted to date implyimply that the wastewater plume does not reach ththee deep aquifaquiferer and may remainremain more concentratconcentrateded in the upper levels of the aquifaquifer.er. AdditionAdditionalal sampling of wells in ththee shallow aqaquiferuifer needs ttoo be completed to ququantifyantify the phosphorus tratransportnsport to the lake.lake.

For the sites sampled by Bain (2002), Figure 1010 shows sites G-2, G-4, G-5, G-7, and G-8 with mean groundwater TP concentrationconcentrationss in the mid to higher rarangesnges above background levelslevels (>40(>40 ug/L). The remaining wells (G-1, G-3, and G-6) show mean groundwater TP concentconcentrationsrations inin the lower rangesranges near oorr below background levelslevels (<40 ug/ug/L).L). Detailed depth and hhydrogeologicydrogeologic informationinformation for sites G-1 through G-8 was not susuppliedpplied by Bain (2002) anandd is currently not known at this point. However, Bain (2002) reports these wells and sitesitess were selectselecteded to char- acterize grogroundwaterundwater in the upper lelevelvel alluvium.

7.3 SODIUM, CHLORIDE, BORON, PH, AND TEMPERATURE

Sodium, chloride, and bboronoron were all measured as indicaindicatorstors that may hhelpelp distingdistinguishuish the between municipal wastewastewaterwater and agricultural or natural phophosphorus.sphorus.

GroundwateGroundwaterr from WWTWWTPP well MW-3 consistently shows some of the highest mean concentrations of sodsodium,ium, chloride, and boron (Table 16).16). Wells MW-2 and MW-3 are also sligslightlyhtly acidic with groundwater pH valvaluesues of 6.90 and 6.95 respectively, while pH values from most other area domestic wells are in tthehe slightly basic range (bet(betweenween 7.0 and 8.0, FigurFigureses 1212 - 15).15). InfiltrationInfiltration of WWTP wastewater may therefore be influencing the sodiusodium,m, chloride, and boron constituents and pH in groundwater since MW-2 and MW-3 are located at the most down-gradient points from the infiltrationinfiltration pondpondss at WWTP.

Boron appears to be the constituent that most closely reflectreflectss the TP anandd OP concentration patterns for the other wells (Figure(Figure 14).14). Most of the shallow wells and those completed in the upper flood sedimsedimentsents aquifer (wells MW-2, MW-3, 188714,188714, 446119446119,, and 17652176520)0) have the higher mean groundwater concentrations of boron (>23 ug/L). The exception isis MW-4 (<20 ug/L), but it should be nnotedoted this well isis lolocatedcated most up-gradient of the WWTP infiltrinfiltrationation ponds. Groundwa- ter from wells completed inin the deepdeeperer basalt rock (432727, 3382022,82022, and 370489) concontainstains lowerlower mean boron conceconcentrationsntrations (<(<2323 ug/L). This pattern is very similar to the TP and OP concentrations fforor the study area wells.

GroundwateGroundwaterr concentration patterns fforor sodium and chloride ffromrom other wells in ththee arareaea are lessless well defdefinedined with no clear patterpatternn based on well depth oorr geologic foformationrmation (Figures 1212 and 13):13): sodsodiumium concentconcentrationsrations are inin the same rangerange (40 –— 60 mg/L) from deep wells 432727 and 382022 (>100 ft) and shallow well 176520176520 ((5959 ft). The lowest chloride concentrconcentrationsations (<7(<7 mg/L) are from deep wellwell 370489 (1(10000 ft) and shshallowallow well 118871488714 (73 ft);ft); however, high chloride concentconcentrationsrations (15 –— 20 mg/L) are also from deep wells 443272732727 and 3382022.82022. Chloride concentrations ffromrom the remaining area wells are in tthehe mid to higher ranges (>7 mg/L).

WRIA 41 LoLowerwer Crab CCreekreek 35 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Table 18. SummarSummaryy of GroundGroundwaterwater PParametersarameters frfromom DomestiDomesticc Wells. Wells

GrouGroundwaterndwater PParametersarameters 443272732727 338202282022 118871488714 337048970489 117652076520 444611946119

Total PhosPhosphorusphorus (u(uglL)g/L) RaRangenge 10 1919 134134 - 141141 16 - 1717 85 - 89 62 MMeanean 1100 1199 113838 116.56.5 8877 6622 MMedianedian 1100 1199 113838 116.56.5 8877 6622 NumberNumberofSamples of Samples nn=1 = 1 nn=1 = 1 nn=2 = 2 nn=2 = 2 nn=2 = 2 nn=1 = 1 OrthOrtho-Phosphoruso-Phosphorus (u(uglL)g/L) RanRangege 1414 1717 129 6 74 72 MMeanean 1144 1177 112929 6 7744 7722 MMedianedian 1144 1177 112929 6 7744 7722 NumberNumberofSamples of Samples nn= = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1 nn= = 1 SodiuSodiumm ((mg/L)mg/L) Range 51.1 52.8 27.1 - 29.1 151151 - 161161 55.4 - 57.2 33.1 MMeanean 551.11.1 552.82.8 228.18.1 115656 556.36.3 333.13.1 MMedianedian 551.11.1 552.82.8 228.18.1 115656 556.36.3 333.13.1 NumberNumberofSamples of Samples nn=1 = 1 nn=1 = 1 nn=2 = 2 nn=2 = 2 nn=2 = 2 nn=1 = 1 ChloriChloridede ((mg/L)mg/L) Range 16.6 17.117.1 4.9 - 7.5 0.6 - 2.6 11.5 - 12.1 7.9 MMeanean 116.66.6 117.17.1 66.2.2 11.6.6 111.81.8 77.9.9 MMedianedian 116.66.6 117.17.1 66.2.2 11.6.6 111.81.8 77.9.9 Number of SSamplesamples n = 1 n = 1 n = 2 n = 2 n = 2 n = 1 BBoronoron ((uglL)ug/L) Range 20.2 20.2 34.8 - 37.5 19.5 - 21.0 32.9 - 34.5 23.1 MMeanean 220.20.2 220.20.2 336.26.2 220.30.3 333.73.7 223.13.1 MMedianedian 220.20.2 220.20.2 336.26.2 220.30.3 333.73.7 223.13.1 Number of SSamplesamples n = 1 n = 1 n = 2 n = 2 n = 2 n = 1 pH RRangeange 7.24 7.34 7.5 8.0 7.7 7.9 MMeanean 77.24.24 77.34.34 77.5.5 88.0.0 77.7.7 77.9.9 MMedianedian 77.24.24 77.34.34 77.5.5 88.0.0 77.7.7 77.9.9 NumberNumberofSamples of Samples nn=1 = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1 TemTemperatureperature (C(C)) RangRangee 11.9 13.7 11.7 14.814.8 12.9 12.9 MMeanean 111.91.9 113.73.7 111.71.7 114.84.8 112.92.9 112.92.9 MMedianedian 111.91.9 113.73.7 111.71.7 114.84.8 112.92.9 112.92.9 NumberNumberofSamples of Samples nn=1 = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1 nn=1 = 1

Mean groundwater temptemperatureseratures are generally higher at the WWTP wells than the ototherher wells. However, thithiss may be bebecausecause of seseasonalasonal influinfluence;ence; the WWWTPWTP wells include grougroundwaterndwater temperatures recordedrecorded dduringuring the susummermmer montmonthshs while temperatures foforr the other wells were recorded duduringring the fall and winter (Figure 16).16).

Elevated concentrations of phosphorphosphorusus in shashallowllow wells is ddueue to greategreaterr susceptibility of these wells to surfsurfaceace sourcesourcess of phosphorphosphorus,us, particuparticularlylarly inin the highighlyhly permeabpermeablele upper soil and allu- vial zones in the area. Higher concenconcentrationstrations of pphosphorushosphorus ((100100 - 250 ug/L ortho-phosphorus) inin shallow grgroundwateroundwater have also been reported by Pitz (2003)(2003) inin samples from two piezome- ters installeinstalledd in lake sesedimentsdiments on the east shorshoree of the lake north of, anandd within Cascade Val- ley.ley. Anthropogenic soursourcesces localocatedted up-gradient of the piezopiezometersmeters such as municipmunicipalal wastewater, leachateleachate from septic drain fields, and lleakageeakage from sewer systems have been identidentifiedified as the primary sources of pphosphorushosphorus in groundwater discharging to the lake.

WRIA 41 LoLowerwer Crab CCreekreek _ 36 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Figure 10.10. Total Phosphorus CoConcentrationsncentrations –— Domestic, Figure 11. OOrtho-Phosphorusrtho-Phosphorus CoConcentrationsncentrations —– DoDo-- WWTP MonMonitoringitoring wwells,ells, and Bain (2002) Wells. mestic and WWTP Monitoring Wells.

5-1446119 0446119 MW 4 (3-? '1') ‘ MW}0. “F" MW SEQMw—Z WIN—3‘19”“! _13§714 138714

(3-30 .94 ' _G-5 G-ZV‘ 3

G-1 432727 432727 . _G-6 C C.

175529 0382022 176520{-3 0332022

TP (ug/L) ..::' 372439 Ortho-P (ug/L) 372439 0 <20 6-8 G <10

0 20 - 40 0 1D - 4U 41 - 30 41 - 70 81 - 120 71 - 11° _ 121-160 “1'14” ‘ >ZDUU . >1500

E: ‘_ BE .._l l

WRIA 41 LoLowerwer Crab CCreekreek . 37 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Figure 12. Sodium ConcConcentrationsentrations —– DomesDomestictic anandd WWTP momoni-ni- Figure 13. Chloride concconcentrationsentrations - DomesDomestictic anandd WWTP MoMoni-ni- tor wwells.ells. toring wwells.ells.

(3446119 (2445119 W_4 ' Mw_4 xx ‘1') MW_3C>(,1 MW_2 MW_3 QC): MW_2 133714 188714

4.352727 432727 (1,-

176520 0 (Z;- 1::2' 332022 176529J 332022

SOdIUm- (mg/L) 370439‘ Chloride (mg/L) 370.439 G <25 ‘ <2 c,- 25 - 30 Q 2 _ 7 31 ' 40 7.5 - 1o “'60 C- 11-15 61 - 90 (3- 16 - 20 0 >150 6 >45

0%; W83 0 05 1 1.5 2 Mlies " ‘1' BE: 7L

WRIA 41 Lower Crab Creek 38 WRIA 41 Lower Crab Creek . 38 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Figure 14. Boron ConConcentrationscentrations –— Domestic anandd WWTP Moni- Figure 15. pH Values - Domestic and WWTP Monitor Wells. tor Wells.

(3446119 o445119 MN 4 ll./|W_4 O — MW 3.‘4:‘Mw_2 “WV—3“? MN—Z " 133714 188714

432727 432727 0 O

176523 Q332022 175523 0332022

Boron (ug/L) 370439 pH 3711489 U ‘ <20 0 5.90 - 6.95 V 20 ' 22 O 7.24 23 ‘ 25 »:::. 7.34 26 - 30 . “1,? 7.50 - 7.60 . 31 - 37 _ L) 7.70 a >160 C 7.80 - 8.00 0 05 1 1.5 2Miles i 55:: ‘7 o 0.5 1 1.5 2 Mlles ‘ E 4L l

WRIA 41 LoLowerwer Crab CCreekreek 39 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Figure 16. GGroundwaterroundwater TemperaTemperaturestures -- DomesDomestictic and WWTP Monitor WellsWells..

0446119 MW_4 a} |v|w_3.“:- MW_2 183714

432727 0

17552.2, 3332022

Temperature (C) 3704-89 O 1L7 Q 119 '- 129 3 13-15 E) 157 . 173

0 05 1 15 ZMIies L E 4' l

GroundwateGroundwaterr from the deeper basalt wells contain concentratconcentrationsions of 1010 –— 1919 ug/L total phosphorus, 6 —– 1717 uug/Lg/L ortho-phosphorus, bbothoth near or below backgbackgroundround conceconcentrations.ntrations. TTwowo of the three deeper wells sampled are also locatedlocated on tthehe east shorshoree of the lake inin Cascade Valley, down-gradient from the main phosphorus sources to groundgroundwater.water. Phosphorus transport in groundwater is primarily occurring in the shallow upper flood sediments (Hanford/Ringold For- mations) that are in direct contact witwithh the lake.lake.

7.4 SEPTIC SYSTEMS IN THE REGION

Residential growth in the Moses Lake has inincreasedcreased 12.3%12.3% inin the lastlast ffiveive years. This represents an inincreasecrease of aboaboutut 2000 peopeople.ple. A signifsignificanticant potion of the growth is occurrinoccurringg inin the Cascade Valley and on the eastern shore of Moses Lake, sosouthuth of interstinterstateate 90. Both areas are outside the City limits but inside the Urban GroGrowthwth Boundary. Figure 1717 shows the areas inin the Urban Growth Area (UGA) that are not currently on the City Sewer system. Currently there are about 3,156 acres of lanlandd available fforor residentiaresidentiall developmedevelopmentnt inin the Cascade ValleValley.y. About 917 acres of that total hahass 491 dwelling units with septic systems. There may be more septic systems than this since Grant CountCountyy HealthHealth DistDistrictrict does nonott have systems installedinstalled prior to 19931993 in their electronic ddataata base.

These areas of that are inside the UrUrbanban Growth Boundary are zoned Urban Residential 2 (R2) or 3 (R3). These land uusese designatdesignationsions allow foforr one to four dwelling uniunitsts per acre fforor R2 or four to eight dwelling unitunitss per acre foforr R3 (Grant(Grant County 1991999).9). Total Urban ResideResidentialntial lots in Cascade Valley that do not have sewer service available are approximaapproximatelytely 3,156 acres. Cur- rently at leastleast 917 of the total acres have 491 septsepticic systems. This area isis developindevelopingg rapidly.

WRIA 41 LoLowerwer Crab CCreekreek 40 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

The City will annex parcels and provide sewer uuponpon request from the owners (perso(personalnal commu- nication, GrGrantant County Planning 202006).06). The loloadsads of phosphorus from septic systems could increaseincrease sigsignificantlynificantly as the available lakesidelakeside lalandnd is develodevelopedped prior to annexation and instal- lationlation of a sewer collection system.

Legend - Sewered Area - Known Existing Septic Systems Unaewered Residential Un sewered Agricultural

0 0.5 1 1.5 2 Miles l 52 1..

Figure 17. Current and ppotentialotential devdevelopmentelopment of CCascadeascade Valley using drain fields for ddisposalisposal of residenresidentialtial wwastewater.astewater.

WRIA 41 LoLowerwer Crab CCreekreek 41 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Soils in the area are in tthehe Ephrata and Malaga soil types. Both soils wwereere formed inin glacial oout-ut- wash that is mixed with lloessoess in the upper horizhorizonon and gravelly fine sandy loamloam below. Soils at depths greatgreaterer than 1919 -23 inches vvaryary from gragravellyvelly to extremely gragravellyvelly with permeability greater than 20 inches pperer hour (USDA SCS 1978).1978). The soil reaction ppHH for Ephrata and Malaga soils is in the aalkalinelkaline range with pH from 7.4 –— 8.4. The soils araree calcareoucalcareouss in the substratum (USDA SCS 1978)1978)

Residential drain fields are installed two to three feet deep inin the very gragravellyvelly soils. The Wash- ingtonington State Department of HealthHealth (WA DOH) classifieclassifiess these soils a Type 1A1A soils. The WA DOH guidanguidancece for deign of septic system in Type 11 A soils rerecommendscommends a maximaximummum loloadingading rate of 1.21.2 ggal/ft2/day.al/ft2/day. TThishis isis ththee highighesthest loading raterate allowaallowableble in septsepticic systems. The high loadingloading raterate results in lessless reactionreaction ttimeime with the soil and more rapid satursaturationation of available adsorption sisitestes in the sosoil.il.

Adsorption of phosphorphosphorusus in soils bbelowelow the drain fields varies dependindependingg on texture (sand, silt or clay contcontent)ent) and chechemistry.mistry. PrePredictingdicting removal isis complicated due to the variable distribution of soisoilsls and non equequilibriumilibrium removalremoval processes (Harris(Harris 2002). The lleasteast effectiveffectivee removal of phosphate ooccursccurs in gragravellyvelly calcareous soils (L(Lombardoombardo 2006).

Phosphorous in septsepticic system effluent can be expected to average about 8,000 ug/L TP. Ap- proximately 20 —– 30% of the phosphphosphorusorus is removed in the septic tank (L(Lombardoombardo 2006). A con- servative load estimate to groundwater from septic systems in Cascade Valley can be estimated. Assuming an average septic tank wastewastewater,water, the approximate lloadoad to the ddrainrain field from 491 houses with an average of 3 people per house and 80 gpd/person is 648 kg phosphorus inin six months (April(April through September). IfIf 20% removalremoval occurs inin the drain field the loadload to the ground water would be about 515188 kg TP. ThThee removal in the groundwater matrix isis expected to be lowlow due to the lowlow ironiron content in soils (2-8 mg/kg soil, Dan Nelson, Soil Test Con- sultants, InInc)c) and very hihighgh content ooff gravel inin the substratusubstratum.m. IfIf we assume a 10%10% removal inin the groundwater matrix tthehe total load from exisexistingting septic systems (in the Grant CountCountyy Health District eleelectronicctronic databadatabase)se) is estimated to be 446666 kg TP.

7.5 GROUNDWATER LLOADSOADS FROM WASTEWATER DISPOSAL

The total grgroundwateroundwater load reductioreductionn recommenrecommendedded in the TTMDLMDL is about 752 kg TTPP (Table(Table 2, Carroll 2006). The estimated six month load fromfrom the Larson Wastewater facility isis 601 kg. The estimated loloadad from the existing septsepticic systems isis about 466 kg. The cocombinedmbined load from wastewater disposal inin Cascade Valley is estimestimatedated to be 11067067 kg TP over a 6 montmonthh period. IfIf itit isis assumed that all this wastewater TP isis able to reachreach the lake,lake, then reremovalmoval of TP at the Larson Facility and installation of a sewer would reresultsult in very significant loadload reductions to MMosesoses LakeLake.. ..

The time for benefits to occur in the lakelake from cocontrolntrol of wastwastewaterewater TP sources depedependsnds on the travel time inin the aquiferaquifer.. Estimated seepage velocity for the groundwater isis 5 to 600 ffeet/dayeet/day (MWH 20032003).). The soutsouthwesthwest flow path is about 17,30717,307 feet; therefore, the time itit takes wastewater to reach lake may be from 9 years to as short as 30 ddays.ays. Given tthathat the wastewater has been applieappliedd daily for more than 20 years there may be a dedelaylay inin benefits due to the potentially largelarge reservereserve of phosphphosphorusorus in the aaquifer.quifer.

WRIA 41 LoLowerwer Crab CCreekreek 42 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

8.0 CONCLUSIONS

8.1 LAKE WATER QUALQUALITYITY

Low dilution flows from Rocky Ford Coulee inin JuJuly,ly, August, anandd SeptembeSeptemberr contributed to development ooff largelarge bloobloomsms of toxic blue green aalgaelgae in the lake. Water quality was good in JulyJuly,, but TP concentrations wwereere greater than 60 ug/L inin the southsouthernern end of tthehe lake in SSeptember.eptember. Concentrations of toxic blue green aalgaelgae were in a range thathatt the World Health Organization considers a moderate to high risk. This condition can be eexpectedxpected to continue when wet win- ters create conditions susuchch that less water in needed in the summer for irrigation soutsouthh of Moses Lake. The USBR shoulshouldd be encourencouragedaged to move greater amounts of dilution water through Moses Lake inin July and August to reduce this prproblem.oblem. Reduction of eexternalxternal phosphorus loadload to the lakelake will also redreduceuce eutrophieutrophicationcation problproblemsems in the llake.ake.

8.2 GROUNDWATER

Disposal of municipal aandnd residential wastewater appears ttoo be a very significant source of groundwater phosphorus entering Moses Lake. The groundwater wells immediately down gradient of the wastewater disposal site have concentrations of TP, Na, Cl, and B that are similar to the wastewater effluent. There is aboaboutut a 20% reduction in concentration that appearappearss due to dilution from groundwater. The total estimated TP load of groundwater in 2006 that may reach Moses Lake from residential septsepticic systems and municipal wastewater sources isis 10106767 kg TP over a six month period. The estimated loadload isis 1142%42% of the recommenderecommendedd groundwater load reduction frofromm the MoseMosess Lake TMDL and about 32% of the ttotalotal loadload recommendedrecommended by WA DOE for all of Moses Lake.

InstallatiInstallationon of phosphorphosphorusus removal technology at the Larson Wastewater Facility, a sesewerwer col- lectionlection systesystemm inin Cascade Valley, and/or requirerequirementsments for removal of phphosphorusosphorus in residential septic systesystemsms will resulresultt inin a signsignificantificant loadload redreductionuction to Moses Lake. IImplementationmplementation of methods to reduce phosphorus loadloadss will improvimprovee the long tetermrm quality of Moses Lake.

9.0 RECOMMENDATIONS

Future sampling shoshoulduld continue to focus on sources of TTPP inin the wawatershed.tershed. EEvaluationvaluation rere-- quires moving the sampling effort ououtt of the lakelake and on to ththee land. Recommended actions for 2007 are:

•0 No lake sampling is rerecommendedcommended forfor 2007. InIn 22008008 the lake should be sampled to maintain the data base ddevelopedeveloped by MLIRD with whole lake assessment once every 5 years. •0 Organize a one time sampling of all shallow wells completecompletedd in the uppupperer flood depdepositsosits and used in the TCE pollution study. WQE has been given access for a one time sampling, but reregulargular sampling on a periodic basis hhasas not been permitted. •0 These data along with modeling information from the TCE pollution cocontrolntrol study will be used to bettbetterer identifyidentify groundwater conditions anandd transport tthroughhrough Cascade Valley intointo Moses Lake.

WRIA 41 LoLowerwer Crab CCreekreek 43 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

•0 Collect and integrate field and sampling data into a groundwater model to quantify the phosphorus loadload from groundwater intointo the lake.lake. Much of the field and gegeologicologic data rre-e- quired by a modeling effort is alreadalreadyy available. •0 Make an estimate of the adsorption capacities of the subsurfasubsurfacece soils and gravels for phosphorus. This will proprovidevide valuable model inputinput and also help determine if groundground-- water will be a long-term source of pphosphorushosphorus lloadingoading to ththee lake. •0 Complete identification of septic systems within City Limits that are not on the sewer system and may be too close to MoMosesses Lake. •0 IdentifyIdentify septic systems ooff concern inin the Crab Creek drainagdrainagee •0 Discuss conconcernscerns about Larson WWTP and sewers with City of Moses Lake and Grant County. •0 Encourage assistanassistancece aandnd cooperation with development of Water PollutPollutionion Control Plan for Moses Lake •0 Pursue soursourcesces of grantgrantss to continucontinuee work and planning inin tthehe watershed.

WRIA 41 LoLowerwer Crab CCreekreek 44 - WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

10.010.0 REFERENCES

Bain, R. C., 1990.1990. Moses Lake CleCleanan Lake ReReport:port: Irrigation Management Report —– Final Re- port. Prepared for Moses Lake IrrigaIrrigationtion and Rehabilitation District, Moses Lake WaWashington.shington.

Bain, R. C. 1998.1998. Moses Lake Area: Water QuaQualitylity Monitoring Report (1997). Prepared for the Moses Lake IrrigationIrrigation anandd RehabilitatRehabilitationion District.

Bain, R.C., 2002. Moses Lake Area —– Water Quality Monitoring Report. PreparePreparedd for Moses Lake IrrigatiIrrigationon and Rehabilitation DiDistrict.strict.

Carroll, J. M. and R.F.RF. Cusimano. 2001. Moses LLakeake Phosphorus TMDL Study –— QuQualityality Assur- ance Project Plan. WA Department of Ecology.

Carroll, J. 22006.006. Moses Lake Phosphorus-Response Model and RecoRecommendationsmmendations to Reduce Phosphorus Loading. PPreparedrepared by Washington StatStatee Department of Ecology. Publication nono.. 06-03-011.

Carlson, R.E.RE. 1977.1977. A Trophic State IndexIndex for Lakes. Limnology and OceanographOceanographyy 23(2):361- 369.

Cusimano, R. F., and Ward, J. W., 1998.1998. Rocky Ford CreCreekek TMDL StStudy.udy. Washington State Department of Ecology. Publication no. 98-326.

Grant CounCountyty 1999.1999. Urban Lands Sub-elemenSub-element.t. InIn Grant County CoComprehensivemprehensive Plan. Sept. 1999.1999. www.www.co.qrant.wa.us/planninq/Lonqranqe/compplan/co.grant.wa.us/planning/Longrange/compplan/

Harris, W. G., 2002. PhPhosphateosphate minerals. Soil Mineralogy with Environmental Applications. J.B. Dixon and D. G. Schulze. Madison, Wisconsin, Soil Science Society of America. 7.

Lombardo, P. 2006. Phosphorus Geochemistry in SSepticeptic TTanks,anks, Soil AAbsorptionbsorption Systems, and GroundwateGroundwater.r. Prepared by LombardLombardoo Associates,Associates, Inc.,Inc., Newton, MA.

MLIRD 2002005.5. Quality Assurance Project Plan for Moses LLakeake IrrigatioIrrigationn and Reclamation Dis- trict: Lake SSamplingampling Program. April 2005. Prepared by WQE Inc for Moses Lake IIrrigationrrigation anandd Reclamation District. AprilApril 2005.

MWH, 2001, Technical MemoranduMemorandum,m, Results ffromrom Steady-State Groundwater Model and Con- taminant Transport Simulations, Moses Lake WWellfieldellfield SupSuperfunderfund Site –— FINAL, Prepared for U.S. Army Corps of Engineers, Seattle District.

MWH, 2003, Final Remedial InvestigationInvestigation and Baseline Risk AssessmAssessmentent Report ((VolumeVolume 1),1), Remedial Investigation/Investigation/FeasibilityFeasibility Study, MosMoseses Lake WWellfieldellfield SupSuperfunderfund Site, Prepared for U.S. Army Corps of Engineers.

Peeler, D. 2004. Status of Moses Lake Water Quality Assessment. Letter to Mr. Glen Rathbone of the Moses Lake IrrigaIrrigationtion and Rehabilitation District. OctOctoberober 29, 2004.

WRIA 41 LoLowerwer Crab CCreekreek 45 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

Pitz, C., 2003, Moses Lake Total MaxiMaximummum Daily Load Groundwater Study, EnEnvironmentalvironmental As- sessment Program, Washington Department of Ecology, Publication Number 03-03-005.

WA DOE 2001. Fact ShSheeteet for State Waste Discharge PermiPermitt ST-8024 - FacilityFacility Name: Moses Lake (LARSON WWTP): SUMMARY. WashingtoWashingtonn State Department of Ecology. Eastern Re- gion Office.

WA DOE 202005.05. EPA Approved CateCategorygory 5 of the WaWaterter Quality Assessment. Approved inin No- vember 2002005.5. http://www.ecy.wa.gohttp://www.ecv.wa.oov/proqrams/wq/303d/2002/2002-index.htmlv/programs/wq/303d/2002/2002-index.html

WA DOE 22006.006. Draft ProgrammatProgrammaticic Environmental ImpactImpact Statement for the Columbia River Water ManaManagementgement ProProgram.gram. Washington State DepartmeDepartmentnt of EcologEcologyy October 5, 2006. Pub- licationlication No. 06-11-030.

Welch, E. B., and C. R. Patmont. 191980.80. Lake Restoration by Dilution: Moses Lake, WWashington.ashington. Water Research 14:13114:1317-1325.7-1325.

WHO, 2006. Guidelines fforor Safe Recreational EnEnvironments.vironments. World Health Organization.

WRIA 41 LoLowerwer Crab CCreekreek 46 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

APPAPPENDIXENDIX 01 –— LLAKEAKE SSAMPLEAMPLE DDATAATA

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APPAPPENDIXENDIX 02 –— LLARSONARSON WWTP EEFFLUENT,FFLUENT, WWTP MMONITORINGONITORING WWELLS,ELLS, AND GGROUNDROUND WATER DDATAATA FOR RRESIDENTIALESIDENTIAL MMONITORINGONITORING WWELLSELLS

WRIA 41 LoLowerwer Crab CCreekreek 48 M WATER 2006 SummarSummaryy ooff GrouGroundwaterndwater aandnd Lake Sampling M QUALITY M ENGINEERING

APPAPPENDIXENDIX 03 —– SSEDIMENTEDIMENT DDATAATA

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APPAPPENDIXENDIX 04 —– CCRABRAB CCREEKREEK WWATERATER DDATAATA

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APPENDIX 5 - RROCKYOCKY FFORDORD FFLowLOW DDATAATA

WRIA 41 Lower Crab Creek 51 M WATER 2006 SummarSummaryy of Groundwater and Lake Sampling M QUALITY M ENGINEERING