Columbia Basin GWMA
Subsurface Geologic Mapping and Hydrogeologic Assessment Project Progress Report
Groundwater Geochemistry Dimitri Vlassopoulos SS Papadopulos and Associates Portland, Oregon Presented at GWMA Board Meeting, Othello, WA January 22, 2009 GWMA Well Sampling 2008
Groundwater Geochemistry, Age and Recharge
Royal City•Wells #1, #2 Shallow-cased water supply wells completed in Wanapum Static water levels steady Mixture of older and “young” water (recharged since 1950s) Recharge from Frenchman Hills sufficient to sustain withdrawals
Moses LakeWell #18 Supply well completed in Wanapum (Frenchman Springs) Static water levels stable Mostly “young” water (post-1950’s) Direct connection to East Low Canal through Roza/Upper Frenchman Springs flow zones
Moses Lake Well #17 Supply well completed in upper Grande Ronde (Sentinel Bluffs) Static water levels declining Mixture of old and “young” water (average recharge age ~6,000 years) Recharge from “young” water component (<20 %) is too small to offset withdrawals Limited connection to surface recharge
Odessa Irrigation well 20 miles east of Moses Lake Well completed in Lower Grande Ronde (Umtanum and Ortley) Static water levels declining Old water (recharge age >10,000 years) No present-day surface recharge sources
Horseshoe Bend Irrigation Wells Shallow (132’) well in use since 1948 (Roza/Alluvium) Deeper (605’) well in basalt (Wanapum and uppermost Grande Ronde) Static water levels stable Predominantly young water in shallow well, predominantly older water in deeper well Relatively low groundwater use area Connection to surface recharge (Sprague Lake) sufficient to recharge shallow well
 
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Last Updated ( Wednesday, 18 March 2009 )
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Subsurface Mapping/Aquifer Assmt 
